Genetic fingerprinting

Genetic fingerprinting

Overview
DNA profiling is a technique employed by forensic scientists to assist in the identification of individuals by their respective DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 profiles. DNA profiles are encrypted sets of numbers that reflect a person's DNA makeup, which can also be used as the person's identifier. DNA profiling should not be confused with full genome sequencing
Full genome sequencing
Full genome sequencing , also known as whole genome sequencing , complete genome sequencing, or entire genome sequencing, is a laboratory process that determines the complete DNA sequence of an organism's genome at a single time...

. It is used in, for example, parental testing and criminal investigation.

Although 99.9% of human DNA sequences are the same in every person, enough of the DNA is different to distinguish one individual from another, unless they are monozygotic twins.
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Encyclopedia
DNA profiling is a technique employed by forensic scientists to assist in the identification of individuals by their respective DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 profiles. DNA profiles are encrypted sets of numbers that reflect a person's DNA makeup, which can also be used as the person's identifier. DNA profiling should not be confused with full genome sequencing
Full genome sequencing
Full genome sequencing , also known as whole genome sequencing , complete genome sequencing, or entire genome sequencing, is a laboratory process that determines the complete DNA sequence of an organism's genome at a single time...

. It is used in, for example, parental testing and criminal investigation.

Although 99.9% of human DNA sequences are the same in every person, enough of the DNA is different to distinguish one individual from another, unless they are monozygotic twins. DNA profiling uses repetitive ("repeat") sequences that are highly variable, called variable number tandem repeats (VNTRs), particularly short tandem repeats (STRs
Short tandem repeat
A short tandem repeat in DNA occurs when a pattern of two or more nucleotides are repeated and the repeated sequences are directly adjacent to each other. The pattern can range in length from 2 to 5 base pairs and is typically in the non-coding intron region...

). VNTR loci
Locus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...

 are very similar between closely related humans, but so variable that unrelated individuals are extremely unlikely to have the same VNTRs.

The DNA profiling technique was first reported in 1984 by Sir Alec Jeffreys
Alec Jeffreys
Sir Alec John Jeffreys, FRS is a British geneticist, who developed techniques for DNA fingerprinting and DNA profiling which are now used all over the world in forensic science to assist police detective work, and also to resolve paternity and immigration disputes...

 at the University of Leicester
University of Leicester
The University of Leicester is a research-led university based in Leicester, England. The main campus is a mile south of the city centre, adjacent to Victoria Park and Wyggeston and Queen Elizabeth I College....

 in England, and is now the basis of several national DNA database
National DNA database
A national DNA database is a government database of DNA profiles which can be used by law enforcement agencies to identify suspects of crimes....

s. Dr. Jeffreys's genetic fingerprinting was made commercially available in 1987, when a chemical company, Imperial Chemical Industries
Imperial Chemical Industries
Imperial Chemical Industries was a British chemical company, taken over by AkzoNobel, a Dutch conglomerate, one of the largest chemical producers in the world. In its heyday, ICI was the largest manufacturing company in the British Empire, and commonly regarded as a "bellwether of the British...

 (ICI), started a blood-testing centre in England.

DNA profiling process


The process begins with a sample of an individual's DNA (typically called a "reference sample"). The most desirable method of collecting a reference sample is the use of a buccal swab
Buccal swab
A buccal swab is a way to collect DNA from the cells on the inside of a person's cheek. Buccal swabs are a relatively non-invasive way to collect DNA samples for testing. Buccal means cheek or mouth....

, as this reduces the possibility of contamination. When this is not available (e.g. because a court order may be needed and not obtainable) other methods may need to be used to collect a sample of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

, saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...

, semen
Semen
Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...

, or other appropriate fluid or tissue from personal items (e.g. toothbrush, razor, etc.) or from stored samples (e.g. banked sperm
Spermatozoon
A spermatozoon is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote...

 or biopsy
Biopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

 tissue). Samples obtained from blood relatives (biological relative) can provide an indication of an individual's profile, as could human remains which had been previously profiled.

A reference sample is then analyzed to create the individual's DNA profile using one of a number of techniques, discussed below. The DNA profile is then compared against another sample to determine whether there is a genetic match.


RFLP analysis


The first methods for finding out genetics used for DNA profiling involved restriction enzyme
Restriction enzyme
A Restriction Enzyme is an enzyme that cuts double-stranded DNA at specific recognition nucleotide sequences known as restriction sites. Such enzymes, found in bacteria and archaea, are thought to have evolved to provide a defense mechanism against invading viruses...

 digestion, followed by Southern blot
Southern blot
A Southern blot is a method routinely used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization. The method is named...

 analysis. Although polymorphism
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...

s can exist in the restriction enzyme cleavage sites, more commonly the enzymes and DNA probes were used to analyze VNTR loci. However, the Southern blot technique is laborious, and requires large amounts of undegraded sample DNA. Also, Karl Brown
Karl Brown
Karl Robert Brown is an English cricketer. He is a right-handed batsman and a right-arm medium-pace bowler who plays for Lancashire. Brown made his first-class debut in 2006 and his list A debut the following year. Between 2005 and 2007, Brown played 15 Youth One Day Internationals...

's original technique looked at many minisatellite
Minisatellite
A minisatellite is a section of DNA that consists of a short series of bases 10-60 bp. These occur at more than 1,000 locations in the human genome...

 loci at the same time, increasing the observed variability, but making it hard to discern individual allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...

s (and thereby precluding parental testing). These early techniques have been supplanted by PCR-based assays.

PCR analysis


With the invention of the polymerase chain reaction
Polymerase chain reaction
The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....

 (PCR) technique, DNA profiling took huge strides forward in both discriminating power and the ability to recover information from very small (or degraded) starting samples. PCR greatly amplifies the amounts of a specific region of DNA, using oligonucleotide
Oligonucleotide
An oligonucleotide is a short nucleic acid polymer, typically with fifty or fewer bases. Although they can be formed by bond cleavage of longer segments, they are now more commonly synthesized, in a sequence-specific manner, from individual nucleoside phosphoramidites...

 primers
Primer (molecular biology)
A primer is a strand of nucleic acid that serves as a starting point for DNA synthesis. They are required for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA...

 and a thermostable DNA polymerase
Taq polymerase
thumb|228px|right|Structure of Taq DNA polymerase bound to a DNA octamerTaq polymerase is a thermostable DNA polymerase named after the thermophilic bacterium Thermus aquaticus from which it was originally isolated by Thomas D. Brock in 1965...

. Early assays such as the HLA
Human leukocyte antigen
The human leukocyte antigen system is the name of the major histocompatibility complex in humans. The super locus contains a large number of genes related to immune system function in humans. This group of genes resides on chromosome 6, and encodes cell-surface antigen-presenting proteins and...

-DQ alpha
HLA-DQA1
Major histocompatibility complex, class II, DQ alpha 1, also known as HLA-DQA1, is a human gene present on short arm of chromosome 6 and also denotes the genetic locus which contains this gene...

 reverse
Allele specific oligonucleotide
An allele-specific oligonucleotide is a short piece of synthetic DNA complementary to the sequence of a variable target DNA. It acts as a probe for the presence of the target in a Southern blot assay or, more commonly, in the simpler Dot blot assay...

 dot blot
Dot blot
right|thumb|350px|Schematic of the use of two [[Allele specific oligonucleotide|ASO]] probes on duplicate Dot-blot filters.A Dot blot is a technique in molecular biology used to detect biomolecules. It represents a simplification of the northern blot, Southern blot, or western blot methods...

 strips grew to be very popular due to their ease of use, and the speed with which a result could be obtained. However they were not as discriminating as RFLP. It was also difficult to determine a DNA profile for mixed samples, such as a vaginal swab from a sexual assault
Sexual assault
Sexual assault is an assault of a sexual nature on another person, or any sexual act committed without consent. Although sexual assaults most frequently are by a man on a woman, it may involve any combination of two or more men, women and children....

 victim.
Fortunately, the PCR method was readily adaptable for analyzing VNTR, particularly STR
Short tandem repeat
A short tandem repeat in DNA occurs when a pattern of two or more nucleotides are repeated and the repeated sequences are directly adjacent to each other. The pattern can range in length from 2 to 5 base pairs and is typically in the non-coding intron region...

 loci.

STR analysis



The method of DNA profiling used today is based on PCR and uses short tandem repeats (STR) a type of VNTR. This method uses highly polymorphic regions that have short repeated sequences of DNA (the most common is 4 bases repeated, but there are other lengths in use, including 3 and 5 bases). Because unrelated people almost certainly have different numbers of repeat units, STRs can be used to discriminate between unrelated individuals. These STR loci
Locus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...

 (locations on a chromosome) are targeted with sequence-specific primers and amplified using PCR. The DNA fragments that result are then separated and detected using electrophoresis
Electrophoresis
Electrophoresis, also called cataphoresis, is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field. This electrokinetic phenomenon was observed for the first time in 1807 by Reuss , who noticed that the application of a constant electric...

. There are two common methods of separation and detection, capillary electrophoresis
Capillary electrophoresis
Capillary electrophoresis , also known as capillary zone electrophoresis , can be used to separate ionic species by their charge and frictional forces and hydrodynamic radius. In traditional electrophoresis, electrically charged analytes move in a conductive liquid medium under the influence of an...

 (CE) and gel electrophoresis
Gel electrophoresis
Gel electrophoresis is a method used in clinical chemistry to separate proteins by charge and or size and in biochemistry and molecular biology to separate a mixed population of DNA and RNA fragments by length, to estimate the size of DNA and RNA fragments or to separate proteins by charge...

.

Each STR is polymorphic, but the number of alleles is very small. Typically each STR allele will be shared by around 5 - 20% of individuals. The power of STR analysis comes from looking at multiple STR loci simultaneously. The pattern of alleles can identify an individual quite accurately. Thus STR analysis provides an excellent identification tool. The more STR regions that are tested in an individual the more discriminating the test becomes.

From country to country, different STR-based DNA-profiling systems are in use. In North America, systems which amplify the CODIS 13 core loci are almost universal, while in the UK the SGM+ 10 loci system (which is compatible with The National DNA Database
National DNA database
A national DNA database is a government database of DNA profiles which can be used by law enforcement agencies to identify suspects of crimes....

), is in use. Whichever system is used, many of the STR regions used are the same. These DNA-profiling systems are based on multiplex reactions, whereby many STR regions will be tested at the same time.

The true power of STR analysis
STR analysis
Short tandem repeat analysis is a molecular biology method used to compare specific loci on DNA from two or more samples. A short tandem repeat is a microsatellite, consisting of a unit of two to thirteen nucleotides repeated hundreds of times in a row on the DNA strand. STR analysis measures...

 is in its statistical power of discrimination. Because the 13 loci that are currently used for discrimination in CODIS are independently assorted (having a certain number of repeats at one locus doesn't change the likelihood of having any number of repeats at any other locus), the product rule for probabilities can be applied. This means that if someone has the DNA type of ABC, where the three loci were independent, we can say that the probability of having that DNA type is the probability of having type A times the probability of having type B times the probability of having type C. This has resulted in the ability to generate match probabilities of 1 in a quintillion (1 with 18 zeros after it) or more. However, DNA database searches showed much more frequent than expected false DNA profile matches. Moreover, since there are about 12 million monozygotic twins on Earth, the theoretical probability is not accurate.

In practice, the risk of contaminated-matching is much greater than matching a distant relative, such as a sample being contaminated from nearby objects, or from left-over cells transferred from a prior test. Logically, the risk is greater for matching the most common person in the samples: everything collected from, or in contact with, a victim is a major source of contamination for any other samples brought into a lab. For that reason, multiple control-samples are typically tested, to ensure that they stayed clean, when prepared during the same period as the actual test samples. Unexpected matches (or variations) in several control-samples indicates a high probability of contamination for the actual test samples. In a relationship test, the full DNA profiles should differ (except for twins), to prove that a person wasn't actually matched as being related to their own DNA in another sample.

AmpFLP


Another technique, AmpFLP, or amplified fragment length polymorphism was also put into practice during the early 1990s. This technique was also faster than RFLP analysis and used PCR to amplify DNA samples. It relied on variable number tandem repeat
Variable number tandem repeat
A Variable Number Tandem Repeat is a location in a genome where a short nucleotide sequence is organized as a tandem repeat. These can be found on many chromosomes, and often show variations in length between individuals. Each variant acts as an inherited allele, allowing them to be used for...

 (VNTR) polymorphisms to distinguish various alleles, which were separated on a polyacrylamide gel using an allelic ladder (as opposed to a molecular weight ladder). Bands could be visualized by silver staining the gel. One popular locus for fingerprinting was the D1S80 locus. As with all PCR based methods, highly degraded DNA or very small amounts of DNA may cause allelic dropout (causing a mistake in thinking a heterozygote is a homozygote) or other stochastic effects. In addition, because the analysis is done on a gel, very high number repeats may bunch together at the top of the gel, making it difficult to resolve. AmpFLP analysis can be highly automated, and allows for easy creation of phylogenetic trees based on comparing individual samples of DNA. Due to its relatively low cost and ease of set-up and operation, AmpFLP remains popular in lower income countries.

DNA family relationship analysis


Using PCR technology, DNA analysis is widely applied to determine genetic family relationships such as paternity, maternity, siblingship and other kinships.

During conception, the father’s sperm cell and the mother’s egg cell, each containing half the amount of DNA found in other body cells, meet and fuse to form a fertilized egg, called a zygote. The zygote contains a complete set of DNA molecules, a unique combination of DNA from both parents. This zygote divides and multiplies into an embryo and later, a full human being.

At each stage of development, all the cells forming the body contain the same DNA—half from the father and half from the mother. This fact allows the relationship testing to use all types of all samples including loose cells from the cheeks collected using buccal swabs, blood or other types of samples.

While a lot of DNA contains information for a certain function, there is some called junk DNA, which is currently used for human identification. At some special locations (called loci) in the junk DNA, predictable inheritance patterns were found to be useful in determining biological relationships. These locations contain specific DNA markers that DNA scientists use to identify individuals. In a routine DNA paternity test, the markers used are Short Tandem Repeats (STRs), short pieces of DNA that occur in highly differential repeat patterns among individuals.

Each person’s DNA contains two copies of these markers—one copy inherited from the father and one from the mother. Within a population, the markers at each person’s DNA location could differ in length and sometimes sequence, depending on the markers inherited from the parents.

The combination of marker sizes found in each person makes up his/her unique genetic profile. When determining the relationship between two individuals, their genetic profiles are compared to see if they share the same inheritance patterns at a statistically conclusive rate.

For example, the following sample report from this commercial DNA paternity testing laboratory Universal Genetics signifies how relatedness between parents and child is identified on those special markers:
DNA Marker Mother Child Alleged father
D21S11 28, 30 28, 31 29, 31
D7S820 9, 10 10, 11 11, 12
TH01 14, 15 14, 16 15, 16
D13S317 7, 8 7, 9 8, 9
D19S433 14, 16.2 14, 15 15, 17


The partial results indicate that the child and the alleged father’s DNA match among these five markers. The complete test results show this correlation on 16 markers between the child and the tested man to draw a conclusion of whether or not the man is the biological father.

Scientifically, each marker is assigned with a Paternity Index (PI), which is a statistical measure of how powerfully a match at a particular marker indicates paternity. The PI of each marker is multiplied with each other to generate the Combined Paternity Index (CPI), which indicates the overall probability of an individual being the biological father of the tested child relative to any random man from the entire population of the same race. The CPI is then converted into a Probability of Paternity showing the degree of relatedness between the alleged father and child.

The DNA test report in other family relationship tests, such as grandparentage and siblingship tests, is similar to a paternity test report. Instead of the Combined Paternity Index, a different value, such as a Siblingship Index, is reported.

The report shows the genetic profiles of each tested person. If there are markers shared among the tested individuals, the probability of biological relationship is calculated to determine how likely the tested individuals share the same markers due to a blood relationship.

Y-chromosome analysis


Recent innovations have included the creation of primers targeting polymorphic regions on the Y-chromosome (Y-STR
Y-STR
A Y-STR is a short tandem repeat on the Y-chromosome. Y-STRs are often used in forensics, paternity, and genealogical DNA testing.-Nomenclature:Y-STRs are assigned names by the HUGO gene nomenclature committee....

), which allows resolution of a mixed DNA sample from a male and female and/or cases in which a differential extraction
Differential extraction
Differential extraction refers to the process by which the DNA from two different types of cells can be extracted without mixing their contents. The most common application of this method is the extraction of DNA from vaginal epithelial cells and sperm cells from sexual assault cases in order to...

 is not possible. Y-chromosomes are paternally inherited, so Y-STR analysis can help in the identification of paternally related males. Y-STR analysis was performed in the Sally Hemings
Sally Hemings
Sarah "Sally" Hemings was a mixed-race slave owned by President Thomas Jefferson through inheritance from his wife. She was the half-sister of Jefferson's wife, Martha Wayles Skelton Jefferson by their father John Wayles...

 controversy to determine if Thomas Jefferson
Thomas Jefferson
Thomas Jefferson was the principal author of the United States Declaration of Independence and the Statute of Virginia for Religious Freedom , the third President of the United States and founder of the University of Virginia...

 had sired a son with one of his slaves.

Mitochondrial analysis


For highly degraded samples, it is sometimes impossible to get a complete profile of the 13 CODIS STRs. In these situations, mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...

 (mtDNA) is sometimes typed due to there being many copies of mtDNA in a cell, while there may only be 1-2 copies of the nuclear DNA. Forensic scientists amplify the HV1 and HV2 regions of the mtDNA, then sequence each region and compare single-nucleotide differences to a reference. Because mtDNA is maternally inherited, directly linked maternal relatives can be used as match references, such as one's maternal grandmother's daughter's son. A difference of two or more nucleotides is generally considered to be an exclusion. Heteroplasmy
Heteroplasmy
Heteroplasmy is the presence of a mixture of more than one type of an organellar genome within a cell or individual...

 and poly-C differences may throw off straight sequence comparisons, so some expertise on the part of the analyst is required. mtDNA is useful in determining clear identities, such as those of missing people when a maternally linked relative can be found. mtDNA testing was used in determining that Anna Anderson
Anna Anderson
Anna Anderson was the best known of several impostors who claimed to be Grand Duchess Anastasia of Russia...

 was not the Russian princess she had claimed to be, Anastasia Romanov.

mtDNA can be obtained from such material as hair shafts and old bones/teeth.

DNA databases



There are now several DNA database
DNA database
A DNA database or DNA databank is a database of DNA data. A DNA database can be used in the analysis of genetic diseases, genetic fingerprinting for criminology, or genetic genealogy. DNA databases may be public or private. These databases do not normally hold DNA except for a short time...

s in existence around the world. Some are private, but most of the largest databases are government controlled. The United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 maintains the largest DNA database
DNA database
A DNA database or DNA databank is a database of DNA data. A DNA database can be used in the analysis of genetic diseases, genetic fingerprinting for criminology, or genetic genealogy. DNA databases may be public or private. These databases do not normally hold DNA except for a short time...

, with the Combined DNA Index System
Combined DNA Index System
The Combined DNA Index System is a DNA database funded by the United States Federal Bureau of Investigation . It is a computer system that stores DNA profiles created by federal, state, and local crime laboratories in the United States, with the ability to search the database to assist in the...

, holding over 5 million records as of 2007. The United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 maintains the National DNA Database (NDNAD), which is of similar size, despite the UK's smaller population. The size of this database, and its rate of growth, is giving concern to civil liberties
Civil liberties
Civil liberties are rights and freedoms that provide an individual specific rights such as the freedom from slavery and forced labour, freedom from torture and death, the right to liberty and security, right to a fair trial, the right to defend one's self, the right to own and bear arms, the right...

 groups in the UK, where police have wide-ranging powers to take samples and retain them even in the event of acquittal.

The U.S. Patriot Act
USA PATRIOT Act
The USA PATRIOT Act is an Act of the U.S. Congress that was signed into law by President George W. Bush on October 26, 2001...

 of the United States provides a means for the U.S. government to get DNA samples from other countries if they are either a division of, or head office of, a company operating in the U.S. Under the act, the American offices of the company can't divulge to their subsidiaries/offices in other countries the reasons that these DNA samples are sought or by whom.

When a match is made from a National DNA Databank to link a crime scene to an offender who has provided a DNA Sample to a databank that link is often referred to as a cold hit. A cold hit is of value in referring the police agency to a specific suspect but is of less evidential value than a DNA match made from outside the DNA Databank.

Considerations when evaluating DNA evidence


In the early days of the use of genetic fingerprinting as criminal evidence, juries were often swayed by spurious statistical arguments by defense lawyers along these lines: given a match that had a 1 in 5 million probability of occurring by chance, the lawyer would argue that this meant that in a country of say 60 million people there were 12 people who would also match the profile. This was then translated to a 1 in 12 chance of the suspect being the guilty one. This argument is not sound unless the suspect was drawn at random from the population of the country. In fact, a jury should consider how likely it is that an individual matching the genetic profile would also have been a suspect in the case for other reasons. Another spurious statistical argument is based on the false assumption that a 1 in 5 million probability of a match automatically translates into a 1 in 5 million probability of innocence and is known as the prosecutor's fallacy
Prosecutor's fallacy
The prosecutor's fallacy is a fallacy of statistical reasoning made in law where the context in which the accused has been brought to court is falsely assumed to be irrelevant to judging how confident a jury can be in evidence against them with a statistical measure of doubt...

.

When using RFLP, the theoretical risk of a coincidental match is 1 in 100 billion (100,000,000,000), although the practical risk is actually 1 in 1000 because monozygotic twins are 0.2% of the human population. Moreover, the rate of laboratory error is almost certainly higher than this, and often actual laboratory procedures do not reflect the theory under which the coincidence probabilities were computed. For example, the coincidence probabilities may be calculated based on the probabilities that markers in two samples have bands in precisely the same location, but a laboratory worker may conclude that similar—but not precisely identical—band patterns result from identical genetic samples with some imperfection in the agarose gel. However, in this case, the laboratory worker increases the coincidence risk by expanding the criteria for declaring a match. Recent studies have quoted relatively high error rates which may be cause for concern. In the early days of genetic fingerprinting, the necessary population data to accurately compute a match probability was sometimes unavailable. Between 1992 and 1996, arbitrary low ceilings were controversially put on match probabilities used in RFLP analysis rather than the higher theoretically computed ones. Today, RFLP has become widely disused due to the advent of more discriminating, sensitive and easier technologies.

Since 1998 the DNA profiling system supported by The National DNA Database in the UK is the SGM+ DNA profiling system which includes 10 STR regions and a sex indicating test. STRs
Short tandem repeat
A short tandem repeat in DNA occurs when a pattern of two or more nucleotides are repeated and the repeated sequences are directly adjacent to each other. The pattern can range in length from 2 to 5 base pairs and is typically in the non-coding intron region...

 do not suffer from such subjectivity and provide similar power of discrimination (1 in 10^13 for unrelated individuals if using a full SGM+ profile). It should be noted that figures of this magnitude are not considered to be statistically supportable by scientists in the UK, for unrelated individuals with full matching DNA profiles a match probability of 1 in a billion is considered statistically supportable. However, with any DNA technique, the cautious juror should not convict on genetic fingerprint evidence alone if other factors raise doubt. Contamination with other evidence (secondary transfer) is a key source of incorrect DNA profiles and raising doubts as to whether a sample has been adulterated is a favorite defense technique. More rarely, chimerism is one such instance where the lack of a genetic match may unfairly exclude a suspect.

Evidence of genetic relationship


It's also possible to use DNA profiling as evidence of genetic relationship, but testing that shows no relationship is absolutely certain. While almost all individuals have a single and distinct set of genes, rare individuals, known as "chimeras
Chimera (genetics)
A chimera or chimaera is a single organism that is composed of two or more different populations of genetically distinct cells that originated from different zygotes involved in sexual reproduction. If the different cells have emerged from the same zygote, the organism is called a mosaic...

", have at least two different sets of genes. There have been several cases of DNA profiling that falsely suggested that a mother was unrelated to her children.

Fake DNA evidence



The value of DNA evidence has to be seen in light of recent cases where criminals planted fake DNA samples at crime scenes. In one case, a criminal even planted fake DNA evidence in his own body: Dr. John Schneeberger
John Schneeberger
John Schneeberger is a South African former physician who lived and practiced in Canada, who drugged and raped one of his female patients and his stepdaughter...

 raped one of his sedated patients in 1992 and left semen on her underwear. Police drew what they believed to be Schneeberger's blood and compared its DNA against the crime scene semen DNA on three occasions, never showing a match. It turned out that he had surgically inserted a Penrose drain
Penrose drain
A Penrose drain is a surgical device placed in a wound to drain fluid. It consists of a soft rubber tube placed in a wound area, to prevent the build up of fluid.It is named for the American gynecologist Charles Bingham Penrose -Common uses:...

 into his arm and filled it with foreign blood and anticoagulant
Anticoagulant
An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...

s.
The functional analysis of genes and their coding sequences (open reading frames [ORFs]) typically requires that each ORF be expressed, the encoded protein purified, antibodies produced, phenotypes examined, intracellular localization determined, and interactions with other proteins sought. In a study conducted by the life science company Nucleix and published in the journal Forensic Science International, scientists found that an In vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...

 synthesized sample of DNA matching any desired genetic profile can be constructed using standard molecular biology
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...

 techniques without obtaining any actual tissue from that person.

In the case of the Phantom of Heilbronn
Phantom of Heilbronn
The Phantom of Heilbronn, often alternatively referred to as the "Woman Without a Face", was a hypothesized unknown female serial killer whose existence was inferred from DNA evidence found at numerous crime scenes in Austria, France and Germany from 1993 to 2009...

, police detectives found DNA traces from the same woman on various crime scenes in Austria, Germany and France - among them murders, burglaries and robberies. Only after the DNA of the "woman" matched the DNA sampled from the burned body of a male asylum seeker in France, detectives began to have serious doubts about the DNA evidence. In that case, DNA traces were already present on the cotton swabs used to collect the samples at the crime scene, and the swabs had all been produced at the same factory in Austria. The company's product specification said that the swabs were guaranteed to be sterile
Sterilization (microbiology)
Sterilization is a term referring to any process that eliminates or kills all forms of microbial life, including transmissible agents present on a surface, contained in a fluid, in medication, or in a compound such as biological culture media...

, but not DNA-free.

Familial DNA searching


Familial DNA searching (sometimes referred to as “Familial DNA” or “Familial DNA Database Searching”) is the practice of creating new investigative leads in cases where DNA evidence found at the scene of a crime (forensic profile) strongly resembles that of an existing DNA profile (offender profile) in a state DNA database but there is not an exact match. After all other leads have been exhausted, investigators may use specially developed software to compare the forensic profile to all profiles taken from a state’s DNA database in order to generate a list of those offenders most likely to be a close relative of the forensic profile. To eliminate the majority of this list, crime lab technicians conduct Y-STR
Y-STR
A Y-STR is a short tandem repeat on the Y-chromosome. Y-STRs are often used in forensics, paternity, and genealogical DNA testing.-Nomenclature:Y-STRs are assigned names by the HUGO gene nomenclature committee....

 analysis that confirms the familial relationships suggested by the first list. Using standard investigative techniques, authorities are then able to build a family tree. The family tree is populated from information gathered from public records
Public records
Public records are documents or pieces of information that are not considered confidential. For example, in California, when a couple fills out a marriage license application, they have the option of checking the box as to whether the marriage is "confidential" or "Public"...

 and criminal justice records. Investigators rule out family members’ involvement in the crime by finding excluding factors such as sex, living out of state or being incarcerated when the crime was committed. They may also use other leads from the case, such as witness
Witness
A witness is someone who has firsthand knowledge about an event, or in the criminal justice systems usually a crime, through his or her senses and can help certify important considerations about the crime or event. A witness who has seen the event first hand is known as an eyewitness...

 or victim statements, to identify a suspect. Once a suspect has been identified, investigators seek to legally obtain a DNA sample from the suspect. This suspect DNA profile is then compared to the sample found at the crime scene, in accordance with well established and constitutionally accepted practices, to definitively identify the suspect as the source of the crime scene DNA.

Familial DNA database searching was first used to convict Craig Harman of manslaughter in the United Kingdom on April 19, 2004. Currently, familial DNA database searching is not conducted on a national level in the United States. States determine their own policies and decision making processes for how and when to conduct familial searches. The first familial DNA search and subsequent conviction in the United States was conducted in Denver, Colorado
Denver, Colorado
The City and County of Denver is the capital and the most populous city of the U.S. state of Colorado. Denver is a consolidated city-county, located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains...

 in 2008 using software developed under the leadership of Denver District Attorney Mitch Morrissey and Denver Police Department Crime Lab Director Gregg LaBerge. California was the first state to implement a policy for familial searching under then Attorney General, now Governor, Jerry Brown
Jerry Brown
Edmund Gerald "Jerry" Brown, Jr. is an American politician. Brown served as the 34th Governor of California , and is currently serving as the 39th California Governor...

. In his role as consultant to the Familial Search Working Group of the California Department of Justice, former Alameda County Prosecutor Rock Harmon is widely considered to have been the catalyst in the adoption of familial search technology in California. The technique was used to catch the Los Angeles serial killer known as the “Grim Sleeper
Grim Sleeper
Grim Sleeper is the nickname for an alleged serial killer in Los Angeles, California, believed to be responsible for at least ten murders, one suspected and one attempted murder in Los Angeles since 1985. The attacker was dubbed the "Grim Sleeper" because he took a 14-year hiatus from his crimes,...

” in 2010 and more recently led to the arrest of 21-year-old Elvis Garcia on charges of sexual assault and false imprisonment of a woman in Santa Cruz
Santa Cruz, California
Santa Cruz is the county seat and largest city of Santa Cruz County, California in the US. As of the 2010 U.S. Census, Santa Cruz had a total population of 59,946...

 in 2008. In March of 2011 Virginia Governor Bob McDonnell
Bob McDonnell
Robert Francis "Bob" McDonnell is an American politician who has been the 71st Governor of Virginia since January 2010. A former lieutenant colonel in the United States Army, McDonnell served in the Virginia House of Delegates from 1993 to 2006 and served as Attorney General of Virginia from 2006...

 announced that Virginia would begin using familial DNA searches. Other states are expected to follow.

At a press conference in Virginia on March 7, 2011 regarding the East Coast Rapist, Prince William County prosecutor Paul Ebert and Fairfax County Police Detective John Kelly said the case would have been solved years ago if Virginia had used familial DNA searching. Aaron Thomas, the suspected East Coast Rapist, was arrested in connection with the rape of 17 women from Virginia to Rhode Island, but familial DNA was not used in the case.

Critics of familial DNA database searches argue that the technique may be an invasion of an individual’s 4th Amendment
Fourth Amendment to the United States Constitution
The Fourth Amendment to the United States Constitution is the part of the Bill of Rights which guards against unreasonable searches and seizures, along with requiring any warrant to be judicially sanctioned and supported by probable cause...

 rights. Some scholars have pointed out that the privacy concerns surrounding familial searching are no more threatening than other police search techniques. The Ninth Circuit Court of Appeals in United States v. Pool ruled that this practice is somewhat analogous to a witness looking at a photograph of one person and stating that it looked like the perpetrator, which leads law enforcement to show the witness photos of similar looking individuals, one of whom is identified as the perpetrator. Regardless of whether familial DNA searching was the method used to identify the suspect, authorities always conduct a normal DNA test to match the suspect’s DNA with that of the DNA left at the crime scene.

For instance, investigators with Denver District Attorney’s Office successfully identified a suspect in a property theft case using a familial DNA search. In this example, the suspect’s blood left at the scene of the crime strongly resembled that of a current Colorado Department of Corrections prisoner. Using publicly available records, the investigators created a family tree. They then eliminated all the family members who were incarcerated at the time of the offense, as well as all of the females (the crime scene DNA profile was that of a male). Investigators obtained a court order to collect the suspect’s DNA, but the suspect actually volunteered to come to a police station and give a DNA sample. After providing the sample, the suspect walked free without further interrogation or detainment. Later confronted with an exact match to the forensic profile, the suspect pled guilty to criminal trespass at the first court date and was sentenced to two years probation.

Partial DNA Matches


Partial DNA matches are not searches themselves, but are the result of moderate stringency CODIS searches that produce a potential match that shares at least one allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...

 at every locus
Locus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...

. Partial matching does not involve the use of a familial search software, such as those used in the UK and Denver, or additional Y-STR
Y-STR
A Y-STR is a short tandem repeat on the Y-chromosome. Y-STRs are often used in forensics, paternity, and genealogical DNA testing.-Nomenclature:Y-STRs are assigned names by the HUGO gene nomenclature committee....

 analysis, and therefore often misses sibling relationships. Partial matching has been used to identify suspects in several cases in the UK and US and has also been used as a tool to exonerate the falsely accused. Darryl Hunt
Darryl Hunt
Darryl Hunt is an African American man from Winston-Salem, North Carolina who, in 1984, was wrongfully convicted of the rape and murder of a young white newspaper copy editor, Deborah Sykes, but was later exonerated by DNA evidence...

 was wrongly convicted in connection with the rape and murder of a young woman in 1984 in North Carolina. Hunt was exonerated in 2004 when a DNA database search produced a remarkably close match between a convicted felon and the forensic profile from the case. The partial match led investigators to the felon’s brother, Willard E. Brown, who confessed to the crime when confronted by police. A judge then signed an order to dismiss the case with prejudice against Hunt, ending the long ordeal for this innocent man.

Surreptitious DNA collecting


Police forces may collect DNA samples without the suspects' knowledge, and use it as evidence. Legality of this mode of proceeding has been questioned in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

.

In the United States, it has been accepted, courts often claiming that there was no expectation of privacy
Expectation of privacy
In United States constitutional law the expectation of privacy is a legal test which is crucial in defining the scope of the applicability of the privacy protections of the Fourth Amendment to the United States Constitution...

, citing California v. Greenwood
California v. Greenwood
California v. Greenwood, 486 U.S. 35 , was a case in which the Supreme Court of the United States held that the Fourth Amendment does not prohibit the warrantless search and seizure of garbage left for collection outside the curtilage of a home....

 (1985), during which the Supreme Court
Supreme Court of the United States
The Supreme Court of the United States is the highest court in the United States. It has ultimate appellate jurisdiction over all state and federal courts, and original jurisdiction over a small range of cases...

 held that the Fourth Amendment
Fourth Amendment to the United States Constitution
The Fourth Amendment to the United States Constitution is the part of the Bill of Rights which guards against unreasonable searches and seizures, along with requiring any warrant to be judicially sanctioned and supported by probable cause...

 does not prohibit the warrantless
Search warrant
A search warrant is a court order issued by a Magistrate, judge or Supreme Court Official that authorizes law enforcement officers to conduct a search of a person or location for evidence of a crime and to confiscate evidence if it is found....

 search and seizure of garbage
Waste
Waste is unwanted or useless materials. In biology, waste is any of the many unwanted substances or toxins that are expelled from living organisms, metabolic waste; such as urea, sweat or feces. Litter is waste which has been disposed of improperly...

 left for collection outside the curtilage
Curtilage
The curtilage is an important legal term to define the land immediately surrounding a house or dwelling, including any closely associated buildings and structures, but excluding any associated 'open fields beyond'. It defines the boundary within which a home owner can have a reasonable expectation...

 of a home
Home
A home is a place of residence or refuge. When it refers to a building, it is usually a place in which an individual or a family can rest and store personal property. Most modern-day households contain sanitary facilities and a means of preparing food. Animals have their own homes as well, either...

. Critics of this practice underline the fact that this analogy ignores that "most people have no idea that they risk surrendering their genetic identity to the police by, for instance, failing to destroy a used coffee cup. Moreover, even if they do realize it, there is no way to avoid abandoning one’s DNA in public."

In the UK, the Human Tissue Act 2004
Human Tissue Act 2004
The Human Tissue Act 2004 is an Act of the Parliament of the United Kingdom which consolidated previous legislation and created the Human Tissue Authority to "regulate the removal, storage, use and disposal of human bodies, organs and tissue."...

 prohibited private individuals from covertly collecting biological samples (hair, fingernails, etc.) for DNA analysis, but excluded medical and criminal investigations from the offence.

England and Wales


Evidence from an expert who has compared DNA samples must be accompanied by evidence as to the sources of the samples and the procedures for obtaining the DNA profiles. The judge must ensure that the jury must understand the significance of DNA matches and mismatches in the profiles. The judge must also ensure that the jury does not confuse the 'match probability' (the probability that a person that is chosen at random has a matching DNA profile to the sample from the scene) with the 'likelihood ratio' (the probability that a person with matching DNA committed the crime). In 1996 R v. Doheny Phillips LJ gave this example of a summing up, which should be carefully tailored to the particular facts in each case:
Members of the Jury, if you accept the scientific evidence called by the Crown, this indicates that there are probably only four or five white males in the United Kingdom from whom that semen stain could have come. The Defendant is one of them. If that is the position, the decision you have to reach, on all the evidence, is whether you are sure that it was the Defendant who left that stain or whether it is possible that it was one of that other small group of men who share the same DNA characteristics.


Juries should weigh up conflicting and corroborative evidence, using their own common sense and not by using mathematical formulae, such as Bayes' theorem
Bayes' theorem
In probability theory and applications, Bayes' theorem relates the conditional probabilities P and P. It is commonly used in science and engineering. The theorem is named for Thomas Bayes ....

, so as to avoid "confusion, misunderstanding and misjudgment".

Presentation and evaluation of evidence of partial or incomplete DNA profiles


In R v Bates, Moore-Bick LJ said:
“We can see no reason why partial profile DNA evidence should not be admissible provided that the jury are made aware of its inherent limitations and are given a sufficient explanation to enable them to evaluate it. There may be cases where the match probability in relation to all the samples tested is so great that the judge would consider its probative value to be minimal and decide to exclude the evidence in the exercise of his discretion, but this gives rise to no new question of principle and can be left for decision on a case by case basis. However, the fact that there exists in the case of all partial profile evidence the possibility that a "missing" allele might exculpate the accused altogether does not provide sufficient grounds for rejecting such evidence. In many there is a possibility (at least in theory) that evidence exists which would assist the accused and perhaps even exculpate him altogether, but that does not provide grounds for excluding relevant evidence that is available and otherwise admissible, though it does make it important to ensure that the jury are given sufficient information to enable them to evaluate that evidence properly”.

DNA testing in the US


There are state laws on DNA profiling in all 50 states of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Detailed information on database laws in each state can be found at the National Conference of State Legislatures website.

Development of artificial DNA



In August 2009, scientists in Israel raised serious doubts concerning the use of DNA by law enforcement as the ultimate method of identification. In a paper published in the journal Forensic Science International: Genetics, the Israeli researchers demonstrated that it is possible to manufacture DNA in a laboratory, thus falsifying DNA evidence. The scientists fabricated saliva and blood samples, which originally contained DNA from a person other than the supposed donor of the blood and saliva.

The researchers also showed that, using a DNA database, it is possible to take information from a profile and manufacture DNA to match it, and that this can be done without access to any actual DNA from the person whose DNA they are duplicating. The synthetic DNA oligos required for the procedure are common in molecular laboratories.

The New York Times quoted the lead author on the paper, Dr. Daniel Frumkin, saying, "You can just engineer a crime scene... any biology undergraduate could perform this."

Dr. Frumkin perfected a test that can differentiate real DNA samples from fake ones. His test detects epigenetic
Epigenetics
In biology, and specifically genetics, epigenetics is the study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence – hence the name epi- -genetics...

 modifications, in particular, DNA methylation
DNA methylation
DNA methylation is a biochemical process that is important for normal development in higher organisms. It involves the addition of a methyl group to the 5 position of the cytosine pyrimidine ring or the number 6 nitrogen of the adenine purine ring...

. Seventy percent of the DNA in any human genome is methylated, meaning it contains methyl group modifications within a CpG dinucleotide context. Methylation at the promoter region is associated with gene silencing. The synthetic DNA lacks this epigenetic modification, which allows the test to distinguish manufactured DNA from original, genuine, DNA.

It is unknown how many police departments, if any, currently use the test. No police lab has publicly announced that it is using the new test to verify DNA results.

Cases

  • In the 1950s, Anna Anderson
    Anna Anderson
    Anna Anderson was the best known of several impostors who claimed to be Grand Duchess Anastasia of Russia...

     claimed that she was Grand Duchess Anastasia Nikolaevna of Russia
    Grand Duchess Anastasia Nikolaevna of Russia
    Grand Duchess Anastasia Nikolaevna of Russia was the youngest daughter of Tsar Nicholas II of Russia, the last sovereign of Imperial Russia, and his wife Alexandra Fyodorovna....

    . In the 1980s, after her death, samples of her tissue that had been stored at a Charlottesville, Virginia hospital following a medical procedure were tested using DNA fingerprinting, and showed that she bore no relation to the Romanovs.
  • In 1986, Richard Buckland was exonerated, despite having admitted to the rape and murder of a teenager near Leicester
    Leicester
    Leicester is a city and unitary authority in the East Midlands of England, and the county town of Leicestershire. The city lies on the River Soar and at the edge of the National Forest...

    , the city where DNA profiling was first discovered. This was the first use of DNA finger printing in a criminal investigation.
  • In 1987, in the same case as Buckland, British
    United Kingdom
    The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

     baker Colin Pitchfork
    Colin Pitchfork
    Colin Pitchfork is a British criminal, the first convicted of murder based on DNA fingerprinting evidence, and the first to be caught as a result of mass DNA screening. Pitchfork raped and murdered two girls, the first in Narborough, Leicestershire, in November 1983, and the second in Enderby,...

     was the first criminal caught and convicted using DNA fingerprinting.
  • In 1987, genetic fingerprinting was used in criminal court for the first time in the trial of a man accused of unlawful intercourse with a mentally handicapped 14-year-old female who gave birth to his baby.
  • In 1987, Florida
    Florida
    Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

     rapist Tommy Lee Andrews was the first person in the United States to be convicted as a result of DNA evidence, for raping a woman during a burglary; he was convicted on November 6, 1987, and sentenced to 22 years in prison.
  • In 1988, Timothy Wilson Spencer was the first man in Virginia
    Virginia
    The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

     to be sentenced to death through DNA testing, for several rape and murder charges. He was dubbed "The South Side Strangler" because he killed victims on the south side of Richmond, Virginia. He was later charged with rape and first-degree murder and was sentenced to death. He was executed on April 27, 1994. David Vasquez, initially convicted of one of Spencer's crimes, became the first man in America
    United States
    The United States of America is a federal constitutional republic comprising fifty states and a federal district...

     exonerated based on DNA evidence.
  • In 1989, Chicago
    Chicago
    Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

     man Gary Dotson
    Gary Dotson
    Gary Dotson Litke, James. , May 9, 1986 Associated Press report. The Ledger of Lakeland, Florida. Accessed October 23, 2009. is an American man who was the second person to be exonerated of a criminal conviction by DNA evidence...

     was the first person whose conviction was overturned using DNA evidence.
  • In 1991, Allan Legere
    Allan Legere
    Allan Legere is a Canadian murderer and arsonist, also known as the Monster of the Miramichi. On May 3, 1989, Legere escaped from RCMP custody while serving a life sentence at the Atlantic Institution for the murder of shopkeeper John Glendenning, of Black River Bridge, New Brunswick, on the...

     was the first Canadian
    Canada
    Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

     to be convicted as a result of DNA evidence, for four murders he had committed while an escaped prisoner in 1989. During his trial, his defense argued that the relatively shallow gene pool of the region could lead to false positives.
  • In 1992, DNA evidence was used to prove that Nazi
    Nazism
    Nazism, the common short form name of National Socialism was the ideology and practice of the Nazi Party and of Nazi Germany...

     doctor Josef Mengele
    Josef Mengele
    Josef Rudolf Mengele , also known as the Angel of Death was a German SS officer and a physician in the Nazi concentration camp Auschwitz-Birkenau. He earned doctorates in anthropology from Munich University and in medicine from Frankfurt University...

     was buried in Brazil
    Brazil
    Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

     under the name Wolfgang Gerhard.
  • In 1992, DNA from a palo verde tree was used to convict Mark Alan Bogan of murder. DNA from seed pods of a tree at the crime scene was found to match that of seed pods found in Bogan's truck. This is the first instance of plant DNA admitted in a criminal case.
  • In 1993, Kirk Bloodsworth
    Kirk Bloodsworth
    Kirk Noble Bloodsworth is the first American sentenced to death row who was exonerated by DNA fingerprinting, although his death sentence had already been commuted to two consecutive life sentences by the time his exoneration based upon DNA evidence was in the works.An honorably discharged former...

     was the first person to have been convicted of murder
    Murder
    Murder is the unlawful killing, with malice aforethought, of another human being, and generally this state of mind distinguishes murder from other forms of unlawful homicide...

     and sentenced to death
    Capital punishment
    Capital punishment, the death penalty, or execution is the sentence of death upon a person by the state as a punishment for an offence. Crimes that can result in a death penalty are known as capital crimes or capital offences. The term capital originates from the Latin capitalis, literally...

    , whose conviction was overturned using DNA evidence.
  • The 1993 rape and murder of Mia Zapata
    Mia Zapata
    Mia Katherine Zapata was the lead singer for the Seattle punk band The Gits.-Life and career:Zapata was born and raised in Louisville, Kentucky...

    , lead singer for the Seattle punk band The Gits
    The Gits
    The Gits were an American punk rock band, formed in Yellow Springs, Ohio in 1986. Known for their part in the burgeoning Seattle music scene of the early 1990s, their distinct punk rock sound gained a reputation for its bluesy street punk aesthetic...

     was unsolved nine years after the murder. A database search in 2001 failed, but the killer's DNA was collected when he was arrested in Florida for burglary and domestic abuse in 2002.
  • The science was made famous in the United States
    United States
    The United States of America is a federal constitutional republic comprising fifty states and a federal district...

     in 1994 when prosecutors heavily relied on DNA evidence allegedly linking O. J. Simpson
    O. J. Simpson
    Orenthal James "O. J." Simpson , nicknamed "The Juice", is a retired American collegiate and professional football player, football broadcaster, and actor...

     to a double murder
    O. J. Simpson murder case
    The O. J. Simpson murder case was a criminal trial held in Los Angeles County, California Superior Court from January 29 to October 3, 1995. Former American football star and actor O. J...

    . The case also brought to light the laboratory difficulties and handling procedure mishaps which can cause such evidence to be significantly doubted.
  • In 1994, Royal Canadian Mounted Police
    Royal Canadian Mounted Police
    The Royal Canadian Mounted Police , literally ‘Royal Gendarmerie of Canada’; colloquially known as The Mounties, and internally as ‘The Force’) is the national police force of Canada, and one of the most recognized of its kind in the world. It is unique in the world as a national, federal,...

     (RCMP) detectives successfully tested hairs from a cat known as Snowball, and used the test to link a man to the murder of his wife, thus marking for the first time in forensic history the use of non-human DNA to identify a criminal.
  • In 1998, Dr. Richard J. Schmidt
    Richard J. Schmidt
    Richard J. Schmidt is an American physician who was convicted by a Louisiana court in 1998 of attempted murder. The case marked the first time in forensic history that viral DNA was used to prove a link between two people with HIV or AIDS in a criminal trial....

     was convicted of attempted second-degree murder when it was shown that there was a link between the viral DNA of the human immunodeficiency virus
    HIV
    Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

     (HIV) he had been accused of injecting in his girlfriend and viral DNA from one of his patients with AIDS. This was the first time viral DNA fingerprinting had been used as evidence in a criminal trial.
  • In 1999, Raymond Easton, a disabled man from Swindon
    Swindon
    Swindon is a large town within the borough of Swindon and ceremonial county of Wiltshire, in South West England. It is midway between Bristol, west and Reading, east. London is east...

    , England, was arrested and detained for seven hours in connection with a burglary. He was released due to an inaccurate DNA match. His DNA had been retained on file after an unrelated domestic incident some time previously.
  • In May 2000 Gordon Graham murdered Paul Gault at his home in Lisburn, Northern Ireland. Graham was convicted of the murder when his DNA was found on a sports bag left in the house as part of an elaborate ploy to suggest the murder occurred after a burglary had gone wrong. Graham was having an affair with the victim's wife at the time of the murder. It was the first time Low Copy Number DNA was used in Northern Ireland.
  • In 2001, Wayne Butler was convicted for the murder of Celia Douty
    Murder of Celia Douty
    Celia Natasha "Tasha" Douty was a British resort worker who was murdered on Brampton Island in Queensland, Australia. The crime remained unsolved until 2001, when Sydney motor industry finance manager, Wayne Butler, was found guilty. It was the first murder in Australia to be solved using DNA...

    . It was the first murder in Australia
    Australia
    Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

     to be solved using DNA profiling.
  • In 2002, the body of James Hanratty
    James Hanratty
    James Hanratty , a petty criminal with no history of violence, was the eighth-to-last person in the United Kingdom to be hanged after being convicted of the murder of Michael Gregsten at Deadman's Hill on the A6, near the village of Clophill, Bedfordshire, England, on 23 August 1961...

    , hanged in 1962 for the "A6 murder", was exhumed and DNA samples from the body and members of his family were analysed. The results convinced Court of Appeal
    Court of Appeal of England and Wales
    The Court of Appeal of England and Wales is the second most senior court in the English legal system, with only the Supreme Court of the United Kingdom above it...

     judges that Hanratty's guilt, which had been strenuously disputed by campaigners, was proved "beyond doubt". Paul Foot and some other campaigners continued to believe in Hanratty's innocence and argued that the DNA evidence could have been contaminated, noting that the small DNA samples from items of clothing, kept in a police laboratory for over 40 years "in conditions that do not satisfy modern evidential standards", had had to be subjected to very new amplification techniques in order to yield any genetic profile. However, no DNA other than Hanratty's was found on the evidence tested, contrary to what would have been expected had the evidence indeed been contaminated.
  • In 2002, DNA testing was used to exonerate Douglas Echols
    Douglas Echols
    Douglas Echols was wrongfully convicted in a 1986 rape case. In 2002, his charges were finally cleared through DNA testing after he served over five years in prison...

    , a man who was wrongfully convicted in a 1986 rape case. Echols was the 114th person to be exonerated through post-conviction DNA testing.
  • In August 2002, Annalisa Vincenzi was shot dead in Tuscany
    Tuscany
    Tuscany is a region in Italy. It has an area of about 23,000 square kilometres and a population of about 3.75 million inhabitants. The regional capital is Florence ....

    . Bartender Peter Hamkin, 23, was arrested, in Merseyside
    Merseyside
    Merseyside is a metropolitan county in North West England, with a population of 1,365,900. It encompasses the metropolitan area centred on both banks of the lower reaches of the Mersey Estuary, and comprises five metropolitan boroughs: Knowsley, St Helens, Sefton, Wirral, and the city of Liverpool...

    , in March 2003 on an extradition warrant heard at Bow Street Magistrates' Court
    Bow Street Magistrates' Court
    Bow Street Magistrates' Court was the most famous magistrates' court in England for much of its existence, and was located in various buildings on Bow Street in central London close to Covent Garden throughout its history.-History:...

     in London
    London
    London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

     to establish whether he should be taken to Italy
    Italy
    Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

     to face a murder charge. DNA "proved" he shot her, but he was cleared on other evidence.
  • In 2003, Welshman Jeffrey Gafoor was convicted of the 1988 murder of Lynette White, when crime scene evidence collected 12 years earlier was re-examined using STR
    Short tandem repeat
    A short tandem repeat in DNA occurs when a pattern of two or more nucleotides are repeated and the repeated sequences are directly adjacent to each other. The pattern can range in length from 2 to 5 base pairs and is typically in the non-coding intron region...

     techniques, resulting in a match with his nephew. This may be the first known example of the DNA of an innocent yet related individual being used to identify the actual criminal, via "familial searching".
  • In March 2003, Josiah Sutton was released from prison after serving four years of a twelve-year sentence for a sexual assault charge. Questionable DNA samples taken from Sutton were retested in the wake of the Houston Police Department's crime lab scandal of mishandling DNA evidence.
  • In June 2003, because of new DNA evidence, Dennis Halstead, John Kogut and John Restivo won a re-trial on their murder conviction. The three men had already served eighteen years of their thirty-plus-year sentences.
  • The trial of Robert Pickton
    Robert Pickton
    Robert William "Willie" Pickton of Port Coquitlam, British Columbia, Canada is a former pig farmer and serial killer convicted of the second-degree murders of six women. He is also charged in the deaths of an additional twenty women, many of them prostitutes and drug users from Vancouver's...

     (convicted in December 2003) is notable in that DNA evidence is being used primarily to identify the victims, and in many cases to prove their existence.
  • In 2004, DNA testing shed new light into the mysterious 1912 disappearance of Bobby Dunbar
    Bobby Dunbar
    Bobby Dunbar was a 4-year old child whose disappearance and apparent recovery was widely reported in newspapers across the United States in 1912 and 1913. After an eight-month nationwide search, investigators believed that they had found the child in the hands of William Cantwell Walters of...

    , a four-year-old boy who vanished during a fishing trip. He was allegedly found alive eight months later in the custody of William Cantwell Walters, but another woman claimed that the boy was her son, Bruce Anderson, whom she had entrusted in Walters' custody. The courts disbelieved her claim and convicted Walters for the kidnapping. The boy was raised and known as Bobby Dunbar throughout the rest of his life. However, DNA tests on Dunbar's son and nephew revealed the two were not related, thus establishing that the boy found in 1912 was not Bobby Dunbar, whose real fate remains unknown.
  • In 2005, Gary Leiterman was convicted of the 1969 murder of Jane Mixer, a law student at the University of Michigan
    University of Michigan
    The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus of the University of Michigan...

    , after DNA found on Mixer's pantyhose
    Pantyhose
    Pantyhose are sheer, close-fitting legwear, covering the wearer's body from the waist to the feet. Mostly considered to be a woman's and girl's garment, pantyhose appeared in the 1960s, and they provided a convenient alternative to stockings...

     was matched to Leiterman. DNA in a drop of blood on Mixer's hand was matched to John Ruelas, who was only four years old in 1969 and was never successfully connected to the case in any other way. Leiterman's defense unsuccessfully argued that the unexplained match of the blood spot to Ruelas pointed to cross-contamination and raised doubts about the reliability of the lab's identification of Leiterman.
  • In December 2005, Evan Simmons was proven innocent of a 1981 attack on an Atlanta woman after serving twenty-four years in prison. Mr. Clark is the 164th person in the United States and the fifth in Georgia to be freed using post-conviction DNA testing.
  • In March 2009, Sean Hodgson who spent 27 years in jail, convicted of killing Teresa De Simone, 22, in her car in Southampton
    Southampton
    Southampton is the largest city in the county of Hampshire on the south coast of England, and is situated south-west of London and north-west of Portsmouth. Southampton is a major port and the closest city to the New Forest...

     30 years ago was released by senior judges. Tests prove DNA from the scene was not his. British police have now reopened the case.

See also


  • DNA database
    DNA database
    A DNA database or DNA databank is a database of DNA data. A DNA database can be used in the analysis of genetic diseases, genetic fingerprinting for criminology, or genetic genealogy. DNA databases may be public or private. These databases do not normally hold DNA except for a short time...

  • National DNA database
    National DNA database
    A national DNA database is a government database of DNA profiles which can be used by law enforcement agencies to identify suspects of crimes....

  • capillary electrophoresis
    Capillary electrophoresis
    Capillary electrophoresis , also known as capillary zone electrophoresis , can be used to separate ionic species by their charge and frictional forces and hydrodynamic radius. In traditional electrophoresis, electrically charged analytes move in a conductive liquid medium under the influence of an...

     (CE)
  • Forensic identification
    Forensic identification
    Forensic identification is the application of forensic science, or "forensics", and technology to identify specific objects from the trace evidence they leave, often at a crime scene or the scene of an accident. Forensic means "for the courts"....

  • Full genome sequencing
    Full genome sequencing
    Full genome sequencing , also known as whole genome sequencing , complete genome sequencing, or entire genome sequencing, is a laboratory process that determines the complete DNA sequence of an organism's genome at a single time...

  • Gene mapping
    Gene mapping
    Gene mapping, also called genome mapping, is the creation of a genetic map assigning DNA fragments to chromosomes.When a genome is first investigated, this map is nonexistent. The map improves with the scientific progress and is perfect when the genomic DNA sequencing of the species has been...

  • genealogical DNA test
    Genealogical DNA test
    A genealogical DNA test examines the nucleotides at specific locations on a person's DNA for genetic genealogy purposes. The test results are not meant to have any informative medical value and do not determine specific genetic diseases or disorders ; they are intended only to give genealogical...

  • Harvey v. Horan
    Harvey v. Horan
    Harvey v. Horan, 278 F. 3d 370 is a federal court case dealing with felons' rights of access to DNA testing. The Eastern Virginia District Court originally found that felons were entitled access to DNA testing on potentially exculpatory evidence, but this finding was later overturned by the...

  • Identification (biology)
    Identification (biology)
    Identification in biology is the process of assigning a pre-existing individual or class name to an individual organism. Identification of organisms to individual names may be based on individualistic natural body features Identification in biology is the process of assigning a pre-existing...

  • Kinship analysis
    Kinship
    Kinship is a relationship between any entities that share a genealogical origin, through either biological, cultural, or historical descent. And descent groups, lineages, etc. are treated in their own subsections....

  • Parental testing
  • Phantom of Heilbronn
    Phantom of Heilbronn
    The Phantom of Heilbronn, often alternatively referred to as the "Woman Without a Face", was a hypothesized unknown female serial killer whose existence was inferred from DNA evidence found at numerous crime scenes in Austria, France and Germany from 1993 to 2009...

  • Project Innocence
  • restriction fragment length polymorphism
    Restriction fragment length polymorphism
    In molecular biology, restriction fragment length polymorphism, or RFLP , is a technique that exploits variations in homologous DNA sequences. It refers to a difference between samples of homologous DNA molecules that come from differing locations of restriction enzyme sites, and to a related...

     (RFLP)
  • ribotyping
    Ribotyping
    Ribotyping involves the fingerprinting of genomic DNA restriction fragments that contain all or part of the genes coding for the 16S and 23S rRNA. Conceptually, ribotyping is similar to probing restriction fragments of chromosomal DNA with cloned probes ....

  • short tandem repeat
    Short tandem repeat
    A short tandem repeat in DNA occurs when a pattern of two or more nucleotides are repeated and the repeated sequences are directly adjacent to each other. The pattern can range in length from 2 to 5 base pairs and is typically in the non-coding intron region...

     (STR)
  • State of Louisiana v. Frisard
    State of Louisiana v. Frisard
    State of Louisiana v. Frisard, 694 So. 2d 1032 , established a legal precedent in Louisiana stating that a man is strictly liable for his sperm if he engages in consensual sexual contact...



External links