What Your Fingers Tell About You

The technology, created by ArroGen Group, a forensic solutions company based in Greenville, North Carolina and Newcastle, U.K., uses a powder that contains sub-micron particles that adhere to the amino and fatty acids in fingerprint residue. While scientists have long used powders to develop fingerprints, these new materials produce images with higher contrast, better clarity, and less background staining.

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The Fingerprint Molecular Identification (FMID) process, as the company calls it, works like this: Scientists sprinkle the powder on the print at the crime scene, then remove it from the crime scene using lift tape. The samples are sealed and brought to the lab, where they are put into a mass spectrometer that scans the print with a laser. As the machine pans the surface, it vaporizes and ionizes the particles in the powder and molecules in the fingerprint residue, enabling the machine to detect molecular profiles in the residue.

Depending on the level of compounds in the secretions left in the print, the machine can detect not only the sex of the person but whether whomever left the print had consumed drugs like cocaine, marijuana, heroin, or methamphetamine; smoked or chewed nicotine; or had touched a gun or explosives. What’s more, ArroGen says they can detect all this information up to a month after a fingerprint has been left—and they’re testing for the ability to read read prints left as long as a year ago.

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