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Researchers discover how to tell the age of a fingerprint

Within a year, police forensics could be employing the new method of determining which fingerprints are relevant to a crime scene.

Vince Alongi, CC BY 2.0

Police could soon be using a new technique that accurately dates fingerprints, thanks to a new technique developed by researchers at the Netherlands Forensics Institute that can date fingerprints within one to two days, if the print is less than 15 days old.

This isn't quite down to the hour or minute yet -- but the breakthrough means the technique can be developed and refined, right down to the hour.

"It's not quite the Holy Grail of fingerprinting, but it's a very important discovery," NFI fingerprint researcher Marcel de Puit told AFP. "Being able to date the prints means you can determine when a potential suspect was at the crime scene or which fingerprints are relevant for the investigation."

Fingerprinting, a practice that began in the late 19th century, used the unique patterns left behind when a naked finger touches a surface to identify the individual to whom those prints belong. Fingers leave behind sweat and sebaceous matter (from touching the face -- a mix of amino acids, chlorides, fatty acids, and triglycerides).

Previously, attempts to date fingerprints relied on the amounts of these materials, but they were unsuccessful. The NFI team's research, however, discovered that the proportions of these chemicals in relation to each other -- controlling for conditions such as temperature and humidity -- is key to gauging their age.

"The chemicals in these fingerprints can be analysed," De Puit said. "Some disappear over time and it's the relative proportions of these chemicals that allow us to date a fingerprint."

The amino acids in a fingerprint, moreover, may be used to determine more information about the person. For example, if you drink a lot of diet drinks, the aspartame will leave amino acids in your body, which may be left behind in a fingerprint.

The technique will need to be tested on real crime scenes to build up a database of fingerprints before it can be used in prosecutions. The team is hoping that institutions such as the FBI and New Scotland Yard may be interested enough in the research to trial it, with the hopes that it could be fully deployed within a year.