History of Forensic DNA Analysis
DNA typing, since it was introduced in the mid-1980s, has revolutionized forensic science and the ability of law enforcement to match perpetrators with crime scenes. Thousands of cases have been closed and innocent suspects freed with guilty ones punished because of the power of a silent biological witness at the crime scene.
'DNA fingerprinting' or DNA typing (profiling) as it is now known, was first described in 1985 by an English geneticist named Alec Jeffreys. Dr. Jeffreys found that certain regions of DNA contained DNA sequences that were repeated over and over again next to each other. He also discovered that the number of repeated sections present in a sample could differ from individual to individual. By developing a technique to examine the length variation of these DNA repeat sequences, Dr. Jeffreys created the ability to perform human identity tests.
How DNA is used in today's forensics investigation
At the crime scene, forensic scientists collect samples of often-minute biological materials--including blood, bone, hair, body fluids and tissue. A DNA profile is run and a panel of markers is established to identify the contributor of the sample. The DNA profile is then compared to samples lifted from other crime scenes, those taken from suspects and databases of DNA fingerprints collected from other sources. If there is no match, a suspect is ruled out. If there is a match, this doesn't mean that a person is declared guilty, but the likelihood that he was present at the crime scene can't be refuted.
In some cases, when DNA isn't available for comparison, the forensics team may request a sample of a relative's DNA since all humans inherit half of their markers from each parent. Additionally, a comparative database known as CODIS is available to all participating law enforcement agencies.
Read more: The History of DNA Forensics | eHow.com
