Forensics

New Technique to Find Latent Prints at Crime Scenes

A new technique has been developed to assist in finding latent prints at the crime scene. In a crime scene examination, investigators collect items of evidence and process them for possible latent prints. Latent prints are left by chance on a surface when someone touches an item, and represent a partial impression of the unique ridge pattern located on an individual’s fingers and palms.

Evidence that is collected is categorized as nonporous, semi-porous or porous. Nonporous evidence can include weapons, vehicles, glass bottles, and plastic bags. Semi-porous evidence can include magazines, varnished wood, and some plastic materials. Porous evidence includes paper, unfinished wood, and fabrics.

Latent prints on nonporous surfaces can pose a challenge for investigators because they are very fragile. They consist of 99% water and approximately 1% amino acids, lipids, and other compounds that can easily be wiped away if the evidence is not handled carefully.