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Glowing Fingerprints Illuminate Forensic Evidence

By adding a drop of liquid containing crystals to crime scene surfaces, investigators using a UV light will be able to see invisible fingerprints “glow” in about 30 seconds as a result of new CSIRO research. The strong luminescent effect creates greater contrast between the fingerprint and the surface, enabling higher resolution images to be taken for easier and more precise analysis.

CSIRO materials scientist Dr Kang Liang believes that the technique, published in Advanced Materials, could be used for more challenging situations where conventional dusting for fingerprints is not appropriate.

“While police and forensics experts use a range of different techniques, sometimes in complex cases evidence needs to be sent off to a lab where heat and vacuum treatment is applied,” Liang said. “Our method reduces these steps, and because it’s done on the spot, a digital device could be used at the scene to capture images of the glowing prints to run through the database in real time.”

The tiny crystals rapidly bind to fingerprint residue, including proteins, peptides, fatty acids and salts, creating an ultrathin coating that’s an exact replica of the pattern. “Because it works at a molecular level it’s very precise and lowers the risk of damaging the print,” Liang said.

CSIRO successfully tested the method on non-porous surfaces, including windows and wine glasses, metal blades and plastic light switches. “As far as we know, it’s the first time that these extremely porous metal organic framework crystals have been researched for forensics,” Laing said.

Metal organic framework crystals are cheap, react quickly and can emit a bright light. The technique also doesn’t create any dust or fumes, reducing waste and the risk of inhalation.

The method could also have other applications in new biomedical devices and drug delivery.