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Forensic Science

Latent Prints

Photo of Manual Comparison of Latent Prints

Manual Comparison of Latent Prints

Photo of Enlarging the Latent Print Image

Enlarging the Latent Print Image

Photo of Entering Latent Prints into the Automated System

Entering Latent Prints into the Automated System

Latent prints, also known as chance impressions, are a crucial piece of evidence that can be left at a crime scene or on objects recovered from a crime scene. They are most often invisible to the naked eye and need some form of physical or chemical development to make them visible.

When good quality latent prints are collected, the Latent Print Unit can enter the prints into the Automated Latent Print System (ALPS) computer. This computer assists the examiner in locating and retrieving records of known prints that reside in the computer database. The database is used to retrieve a candidate list of possible matching impressions. After the candidate list is received, the latent print examiner conducts the final comparison. As part of the scientific process, any identification is then independently examined by a second latent print examiner to verify the original identification.

For all other latent prints that are suitable for identification purposes, a suspect's inked finger and/or palmprint card must accompany the latent print evidence. This enables the latent print examiner to conduct a manual comparison and render an opinion on whether or not any particular latent print is identified as being made by the subject in question.

Obtaining properly rolled legible fingerprints of individuals known to have been at a crime scene is an important part of an investigation. These rolled inked prints are called elimination prints. Collection of elimination prints allows the latent print examiner to possibly eliminate many of the latent prints that were collected as evidence.