Forensic DNA typing identifies individuals using genetic samples, developed by Sir Alec Jeffreys in 1985. Samples are obtained from bodily fluids, personal items, or buccal swabs. Different techniques are used to create a reference sample, with the most commonly used method being tandem-repeated short analysis. DNA databases help find matches, with the largest content in the US. DNA can also be obtained from family members. Concerns about using DNA in court have decreased due to increased understanding. However, using family members’ DNA has been criticized for being a form of racial profiling.
Forensic DNA typing is the process by which individuals are identified using genetic samples. Two different samples are defined by a series of identification numbers and matched to see if they are equal. Sir Alec Jeffreys of the University of Leicester developed the concept in 1985. Forensic DNA typing is used in a number of investigations, particularly those involving rape and murder, to convict or exonerate suspects.
Forensic DNA typing begins with obtaining DNA samples from individuals. The best sources of these samples are bodily fluids such as saliva, blood and semen. Many people have previously stored samples or DNA may have recently been obtained from personal items. However, the best source of these samples comes from using a buccal swab inside the cheek. A number of techniques are used to create a reference sample and a genetic match is attempted.
Several options for creating DNA samples have been developed. The digestion process is used in restriction fragment length polymorphism. However, this process makes it difficult to identify individual chromosomes. DNA can be most closely identified with small starting samples in the polymerase chain reaction. Again, this technique has limited results when samples are mixed, such as in rape cases. The most commonly used method today is the tandem-repeated short analysis. This uses repeating base sequences in the DNA to identify the correct DNA type.
The world has developed a number of DNA databases that help in finding matches during forensic DNA typing. Each of these stores contains a huge collection of different genetic codes. A forensic scientist uses these existing samples to match a suspect’s DNA. Most of these DNA databases are maintained by governments, with the largest content in the United States. As of 2007, over five million genetic codes were stored in the Combined DNA Index System.
During the 1980s, when DNA typing in forensics was in its infancy, many lawyers and court personnel expressed concern about the concept being used to prosecute or exonerate criminals. However, increased understanding of the science and best practices have led to the admission of DNA into the evidence.
Forensic DNA typing can also use the genetic material of suspects’ family members. This method is useful when no new samples are available from the suspect. There are a number of criticisms of this concept due to the fact that no exact matches are made. In theory, matches between unrelated individuals of the same race are possible. This concept is perhaps a form of racial profiling.
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