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DNA Evidence: What Law Enforcement Officers Should Know

NCJ Number
NIJ Journal Issue: 249 Dated: July 2003 Pages: 10-15
Date Published
July 2003
6 pages
Publication Series
This article instructs police officers in proper methods for collection and management of DNA evidence at crime scenes.
Violent crime scenes often contain a wide variety of biological evidence, most of which can be subjected to DNA testing. Responding officers and investigators should conduct their work at the crime scene as if it were the only opportunity to preserve and recover physical evidence. Keeping DNA evidence untainted until it has been collected and recorded is the most important aspect of managing the evidence. In examining the crime scene, police investigators should take precautions, such as wearing disposable gloves and avoiding touching any other objects while handling such evidence, so as to avoid contamination. Officers should not drink, eat, litter, smoke, or engage in any other behavior that might compromise the crime scene. Any movement or relocation of potential evidence should be avoided. Maintaining a precise chain of custody for all DNA materials collected for testing is critical. Since the DNA of several individuals may be present at a crime scene, officers must ensure that technicians collect the victim's DNA along with the DNA of anyone else who may have been present at the scene. These "elimination samples" help determine whether the evidence is from a suspect or another person. When transporting and storing evidence that may contain DNA, the evidence should be kept dry and at room temperature. It should be placed in paper bags or envelopes and then sealed, labeled, and transported in a way that ensures proper identification and documents a precise chain of custody. The article concludes with a description of the process of DNA testing, along with descriptions of some anticipated advances in the use of DNA technology. 4 suggested readings

Date Published: July 1, 2003