American Academy of Forensic Scientists
Midwestern Association of Forensic Scientists
Fingerprints, palmprints and footprints are impressions of the friction ridge skin present on the palm side of the hand and soles of the feet. When a person touches, grabs, or walks barefoot on a surface, an impression of the friction ridge skin may be left behind. These accidental impressions are called latent prints.
The importance of latent print evidence is its ability to identify an individual. Latent prints can be identified to a single person because the friction ridge skin possesses two key properties: permanence and uniqueness. With the exception of injury, a person has the same fingerprints, palmprints and footprints from before birth until decomposition after death. Additionally, the friction ridge skin has unique characteristics which allow even a small portion of a latent print to be identified to a single person.
Latent prints left on a surface can be visualized through a variety of chemical and physical development techniques. Once visible, the latent print can be photographed and compared to the known inked impressions (including palmprints or footprints) of an individual. Through careful analysis and comparison of the friction ridge skin characteristics in both the unknown latent print and the known inked print, a person may be identified or eliminated as having made the print.
Latent fingerprints and palmprints may be searched through the Automated Fingerprints Identification System (AFIS), a computer-based system which compares unknown prints entered by an examiner to prints in a database. AFIS is a valuable investigative tool, providing new leads to aid in solving crimes.