Latent fingerprints are left accidentally by sweat on the hands and feet, and can be exposed using fingerprint powder or fumes. Analysis of fingerprints can provide evidence about the offender or crime. The Integrated Automatic Fingerprint Identification System (IAFIS) is a national database used by police investigators to obtain more information about fingerprints found at crime scenes.
In forensics, latent fingerprints are marks left at a crime scene that may not be immediately visible to the naked eye. To expose them, technicians use fingerprint powder, fumes, and other techniques. Identifying these fingerprints is an important part of evidence gathering, and many technicians specialize in retrieving fingerprints from crime scenes and laboratory analysis to assist law enforcement in catching criminals.
The hands and feet are covered in a natural secretion from the eccrine glands, which produce sweat, a mixture of water, salts and other trace compounds. Sweat adheres to the friction ridges of the finger and when a finger is placed on a surface such as glass, plastic or wood, an imprint will be left. The body’s natural secretions preserve the fingerprint, which is completely distinct: no two human beings have the same fingerprints.
Latent fingerprints are usually left by accident, because an inattentive criminal did not realize that his or her hands could leave a mark. Sometimes, fingerprints consist of substances other than sweat, such as blood, other bodily fluids, or paint. In this case, they are called patent fingerprints. Part of the analysis performed on fingerprints includes determining what the fingerprint was taken from, as this could provide further evidence about the offender or crime.
When detectives arrive at a crime scene, one of the first things they do after photographing the entire scene is powder for latent fingerprints. This ensures that no fingerprints are lost, even if patent fingerprints are evident, fingerprints easily visible to the naked eye. Special fingerprint powder is gently brushed onto surfaces likely to contain fingerprints to see if any appear. If fingerprints do emerge after dusting, they are photographed and then carefully lifted off with clear tape before being applied to the cards. For difficult surfaces, another process known as fumigation can be used to find these marks. Smoke can be used for very old fingerprints, because it causes a chemical reaction with trace substances that can be left behind, even if the sweat itself has disappeared.
The fingerprints are taken back to a crime lab for analysis, which usually begins with scanning them into a computer and cross-checking them with a criminal database for matches. In the United States, the Integrated Automatic Fingerprint Identification System (IAFIS) is a national database that police investigators can use to obtain more information about fingerprints found at crime scenes. The electronic database contains over 47 million records and can be used to instantly check fingerprints at the crime scene. Fingerprint records for IAFIS come from criminals, as well as citizens who are fingerprinted as part of a routine background check, and the substantial database greatly assists law enforcement agencies in their work.
Protect your devices with Threat Protection by NordVPN
