Chemistry reveals whether fingerprints came from a male or a female

Scientists have developed a technique that distinguishes between male and female fingerprints(Credit: Paul Miller/University at Albany)

The discovery of fresh fingerprints at a crime scene is a promising step towards determining the culprit, though huge databases still need to be sifted through in order to find potential matches and the culprit's prints need to be included in said databases. So what if many of the suspects could be ruled out before this rigorous search even begins? A new fingerprint identification technology is promising to lighten the load for investigators, by revealing whether prints belong to a male or female.

The new approach works on the premise that amino acid levels in the sweat of females are around twice as high as in males. Led by assistant chemistry professor Jan Halámek, a team of researchers from the University at Albany sought to use this biological difference to add another tool to investigators' arsenals.

The technique involves first transferring a fingerprint onto a piece of plastic wrap, where it is treated with a hydrochloric acid solution and then heated. This forces a chemical reaction that sees the water-soluble amino acids migrate into the acidic solution. Here, the team can assess the levels of amino acids and determine which sex the prints came from.

In initial testing where the team used imitation fingerprint samples, the method was able to distinguish between sexes with 99 percent accuracy. They then set up a mock crime scene, where three females left fingerprints on five surfaces, including a computer monitor and a doorknob. The team reports that the technique was successful in determining that the prints belonged to a female.

"One of the main goals for this project was to move toward looking at the chemical content within the fingerprint, as opposed to relying on simply the fingerprint image," Halámek said. "We do not intend to compete with DNA analysis or the databases used for identification. Instead we are aiming at differentiating between demographic groups, and more importantly, we are aiming at making use of fingerprints that are smudged/distorted or that don't have an existing match."

The team is now looking to further improve the new technique, while also developing more identification methods for other attributes that may aid in forensic investigations.

The research was published in the journal Analytical Chemistry.

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