Legal Nurse Consulting News: DNA Fingerprinting and Forensics
Saturday, May 26, 2007
The scene of a crime is a busy, hectic place. People running to and fro collecting evidence in the hope that the criminal may have left some vital clue behind that will lead to his arrest and, later, his conviction. Before 1985, actual fingerprints of the criminal were perhaps the most sought after pieces of evidence. The presence of a fingerprint at the scene, in the right place and combined with other evidence, might be enough to prove ?beyond a reasonable doubt? that a suspect was guilty. Of course, fingerprints can be wiped off or obscured by blood or other fluids at the scene. Gloves might be worn. Fingers might be altered in some way that will obscure the prints. The savvy criminal had many ways to avoid leaving his fingerprints at the scene of the crime. In 1985, Sir Alec Jeffreys at the University of Leicester discovered DNA fingerprinting. DNA fingerprinting opened a new avenue for law enforcement personnel to obtain a positive identification of criminals. This technique is used to match samples of blood, hair, saliva, or semen to one another in the attempt to match the criminal to the crime. These samples can be collected from a variety of sources such as personal items (razors and brushes) or mouth swabs. As for the crime scene, DNA can be collected from many sources as well. For example, in a rape case, semen left by the perpetrator might be compared to a potential suspect in order to exonerate him or arrest him. DNA fingerprinting is useful in other areas as well, such as paternity testing, but the focus of this article will be on uses for forensic science. Although DNA fingerprinting is not completely fool proof, it is very convincing. Each comparison examines 13 regions of DNA, and if 5 regions match, the chance of the DNA coming from the same source is almost certain. It would be very rare, although possible, for samples to appear the same but come from different sources. If 5 regions match, however, this is compelling enough for an attorney to use in trial to convince the jury that the suspect is guilty beyond a reasonable doubt. In the years following its discovery and as the practice of DNA fingerprinting became increasingly common, a database was required to store all of the DNA samples collected. Thus, the Combined DNA Index System (CODIS) was born. This database has over a million DNA samples that have been taken from crime scenes or alleged and convicted criminals. Many of these samples do not have any identification but are stored in case they match a future crime scene or new evidence is discovered for the crime scene from which they were collected. As with the now archaic standard method of fingerprinting, law enforcement personnel can run a DNA sample through CODIS and see if they have a match with any known offenders already in the database. The DNA Identification Act of 1994 allows all of these DNA samples of offenders and crime scene evidence to be sent to the database. An area of concern regarding DNA fingerprinting involves privacy of the person from whom the DNA sample was taken. Just as a credit card report or bank statement contains much personal information, so too might DNA information contain personal information that may be used for purposes other than what the sample was originally intended for. Research is ongoing regarding DNA and new information about DNA is being discovered all the time. For instance, a DNA sample may reveal diseases that the donor has or other private details of the donor?s life. Often, potential suspects have no choice but to offer DNA samples according to court order. This potentially may invade their privacy and place very personal information into other people hands. Although the area of DNA fingerprinting is still being perfected and has some controversial issues surrounding it, it is still a very effective tool used in the area of forensic science. DNA fingerprinting will continue to evolve and the process will be improved upon over time. This tool for identifying potential suspects at crime scenes and convicting criminals during trial is too useful for it to not be utilized to its full potential. The medical, legal, and law enforcement arenas can expect to see promising new research in the area of DNA fingerprinting in the years to come.