Fingerprint Brushes can Contaminate DNA Evidence
An investigator can do simple things to ensure the integrity of DNA evidence. DNA can be transferred from one crime scene to another through tools. For example, fingerprint brushes can become easily contaminated. Brushes can retain the DNA picked up. To make sure you don’t transfer DNA from a brush used at one scene to the next, use a new one at each scene. This is most important on homicide cases where the DNA may be the determining factor. In fact, on homicides, the brush used should become part of your overall evidence. Remember that not only the brush used, but the powder itself can become contaminated. While magnetic applicators can be cleaned with 10% bleach (or you can use disposable ones) fiberglass brushes cannot be easily cleaned and reused. The $6 or $9 you spend on a new brush is a small price to pay for alleviating questions about your evidence.
Keeping contamination of evidence to a minimum is especially critical while investigating a homicide. Homicide crime scenes are ripe for potential DNA evidence. Collect numerous samples. Collect as much evidence as possible. Remember that with today’s technology, even if DNA can’t be lifted from a sample in the present, new methods may be available in the future.
From: Crime Scene Contamination by Dick Warrington