TRACE EVIDENCE

Trace evidence is evidence that may be present at a scene, but its minuteness necessitates special scrutiny. The particular evidence may hold some specific significance in linking a victim, a suspect, a scene, and the activities of what has occurred. An investigator, evidence technician, and other support personnel determine the significance it may play in understanding what happened and who was responsible; a crime lab technician analyzes and interprets the evidence. Trace evidence is based on the philosophy that there must be an exchange of items between individuals and an environment. This exchange – known as Locard’s Principle – includes trace materials that may only be discovered through a deliberate and thorough processing procedure. The clothing of the suspect is a primary source of trace material. Three possibilities exist for developing trace evidence: 1. Trace materials from the victim may have collected on the suspect.2. Trace material from the environment, linking the particular suspect to a particular location, may be present on the suspect. 3. Standards from the suspect must be collected and compared with items collected from the victim and the scene to link the individual to the area and the crime. From the victim, you may find trace evidence collected that came from the suspect. Trace evidence from the scene may also be found, which comes important in cases where a body has been “dumped”. Clothing is a primary accumulator of trace evidence, and care and caution must be taken in handling, collecting, and packaging these articles. If a suspect is still wearing the clothing believed to have been worn at the time of the crime, you should first examine visually for any signs of evidence. The suspect should stand on a clean piece of wrapping paper. As each item of clothing is removed, it should be wrapped separately. After the suspect has removed all his clothing, the wrapping paper should be collected, folded inward, and bagged separately. Never shake or handle possible evidence any more than absolutely necessary. Never place clothing items in a plastic or an air tight container. Moisture causes bacterial growth, which makes analysis unproductive. Never turn the pockets inside-out. The pockets, cuffs, and pants pleats often are receptacles for trace evidence. If trace evidence is removed from clothing prior to sending it off for trace analysis, note the precise location of where the item was recovered.