How does fingerprint evidence work?

On Behalf of | Sep 10, 2021 | Criminal Defense

“Dusting for fingerprints” might not be the only evidence collection process that police perform, but it is the one that most people are familiar with. Law enforcement personnel take great care to find fingerprints at a Pennsylvania crime scene because the recovered evidence could be crucial during a trial. As the saying goes, no two fingerprints are alike, so fingerprints may deliver proof of guilt or innocence.

The fingerprint collection process

The first step involves finding fingerprints, so a skilled crime scene investigator will gravitate to areas likely to contain prints. Dusting for prints allows the dust to collect on oils, making the prints visible.

Modern innovations enhance the process. An electronic scanning device could capture fingerprint images, and those images might find their way into a valuable database.

Once the police recover the fingerprints, they work on finding a match. In generations past, looking at images of prints with a magnifying glass and performing manual comparisons was the established method. Today, advancements in technology make things far less cumbersome. For example, the international automatic fingerprint identification system stores well over 200,000 prints, making it a valuable database.

Fingerprints as evidence in court

A criminal defense strategy may involve challenging the fingerprint evidence. For example, smudged fingerprints might not be anywhere near as conclusive as clean prints. Challenging a smudged fingerprint in court may contribute to a jury’s reasonable doubts. The evidence might never enter into the trial if a judge suppresses it.

Even pristine fingerprints might come with questions. While prints are commonly used as evidence, science suggests that fingerprints don’t always provide reliable identification.

The resulting prosecution might be weak when fingerprints are the only evidence linking a defendant to a crime. Absent other evidence, securing a conviction could prove challenging. The accused person might avoid a conviction when minimal evidence is weak or gets suppressed.