DNA Evidence and Procedures - Essay Example

Though DNA is used by the body to create the physical characteristics of hair color, eye color, and height, it can only be used to match a suspect to a sample and can not determine their physical characteristics. Advances in DNA technology have revolutionized forensic science since its introduction in the mid 1980s. It is used to bring evidence against a suspect as well as exonerate innocent people. As investigators, law enforcement is generally concerned with a few key issues with respect to DNA evidence These issue involve maintaining the integrity of the evidence and the credibility of its evidentiary value.

These are: The crime scene is the first line of defense in maintaining credible DNA evidence. To minimize the possibility of contamination the incidental activity must be reduced at the crime scene. Only critical personnel should have any initial access until all samples are collected. According to the President's DNA Initiative (2007), "It is important for all law enforcement personnel at the crime scene to make a conscious effort to refrain from smoking, eating, drinking, littering or any other actions which could compromise the crime scene".

In addition, it is suggested that all first responders be trained in DNA collection and preservation techniques. Investigators must tediously search for small amounts of DNA evidence available at the scene. This may be small blood spatters, hair, skin tissue evidence found under fingernails, and clothing that contains body fluids. Suspects may be swabbed for saliva or DNA may be obtained from an object they have contacted. In the case of rape or sexual assault, the Department of Justice guidelines dictate that, ".

evidence that may be inside or on a victim's body should only be collected by a physician or sexual assault nurse examiner" (Understanding DNA evidence, 2007). Initial contact with an assault victim should stress the importance of not changing clothes or showering before evidence can be collected. Evidence needs to be clearly labeled and identified as to where and when it was collected in a manner that will maintain a proper chain of custody. Samples should be kept dry and need be sealed to prevent contamination and stored at room temperature to prevent degradation (President's DNA Initiative, 2007).

The National Institute of Justice mandates that evidence that may contain DNA should not be placed in plastic bags as plastic retains moisture which could damage and degrade the DNA sample (What every law enforcement officer should know about DNA, 1999). Direct sunlight and heat can also damage samples and it is recommended that the sample be transported as quickly as reasonable to an appropriate storage area. It is recommended that long-term storage be maintained only by a qualified facility or laboratory.

In the 2003 Summit Report, the National Institute of Justice warned, "If law enforcement officers, medical personnel, and crime lab technicians are not trained to recognize, collect, preserve, transport, and store DNA evidence, thenits use may be compromised or even invalidated". Maintaining the integrity of the DNA evidence is vital if it is to have any value in the courtroom. Contamination is the greatest threat to the usability of DNA evidence. DNA evidence runs the risk of being contaminated when DNA from