Crime Scene Investigator Network Newsletter

The purpose of the walk through is to note the location of potential evidence and to mentally outline how the scene will be examined. The walk through begins as close to the point of entry as possible. The first place the investigators should examine is the ground on which they are about to tread. If any evidence is observed, then a marker should be placed at the location as a warning to others not to step on the item of interest.

A good technique to use indoors on hard floors is the oblique lighting technique (also known as side lighting). A good flashlight with a strong concentrated beam is the only tool needed. The room should be darkened as much as possible. If a light switch which a suspect may have touched needs to be turned off, then make sure the switch has been dusted for fingerprints first. Do not close any blinds or shades until after all general photographs have been taken. In the side lighting technique, a flashlight is held about one inch from the floor. The beam is then angled so that it just sweeps over the floor surface and is almost parallel to the surface. The light is then fanned back and forth. Any evidence, such as trace evidence and shoeprints, will show up dramatically. Under normal lighting conditions, this evidence may be barely visible or completely invisible.

As the walk through progresses, the investigators should make sure their hands are occupied by either carrying notebooks, flashlights, pens, etc. or by keeping them in their pockets. This is to prevent depositing of unwanted fingerprints at the scene. As a final note on the walk through, the investigators should examine whatever is over their heads (ceiling, tree branches, etc.). These areas may yield such valuable evidence as blood spatters and bullet holes. Once the walk through is completed, the scene should be documented with videotape, photographs, and/or sketches.

Documenting the Crime Scene
If available, a video camera is the first step to documenting a crime scene. Videotape can provide a perspective on the crime scene layout which cannot be as easily perceived in photographs and sketches. It is a more natural viewing medium to which people can readily relate, especially in demonstrating the

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