Forensic hand bacteria breakthrough could open doors to future use of bacteria analysis in criminal investigations.

Forensic hand bacteria breakthrough could open doors to future use of bacteria analysis in criminal investigations.


1st May 2010

Major discoveries by forensic scientists may have found a revolutionary way to identify individuals using unique, telltale types of hand bacteria left behind on objects like keyboards and computer mice according to the University of Colorado Boulder study.

The new discovery could see bacteria analysis being implemented in criminal investigations including fraud, embezzlement and theft. The Boulder study showed that "personal" bacterial communities living on the fingers and palms of individual computer users that were deposited on keyboards and mice matched the bacterial DNA signatures of users much more closely than those of random people. While the development of the technique is continuing, it could provide a way for forensics experts to independently confirm the accuracy of DNA and fingerprint analyses, says CU-Boulder Assistant Professor Noah Fierer, chief author on the study.

"Each one of us leaves a unique trail of bugs behind as we travel through our daily lives," said Fierer, an assistant professor in CU-Boulder's ecology and evolutionary biology department. "While this project is still in its preliminary stages, we think the technique could eventually become a valuable new item in the toolbox of forensic scientists."

The study was published March 15 in the Proceedings of the National Academy of Sciences. Using powerful gene-sequencing techniques a team of forensic experts swabbed bacterial DNA from individual keys on three personal computers and matched them up to bacteria on the fingertips of keyboard owners, comparing the results to swabs taken from other keyboards never touched by the subjects. The bacterial DNA from the keys matched much more closely to bacteria of keyboard owners than to bacterial samples taken from random fingertips and from other keyboards.

In a second test, the team swabbed nine keyboard mice that had not been touched in more than 12 hours and collected palm bacteria from the mouse owners. The team compared the similarity between the owner's palm bacteria and owner's mouse with 270 randomly selected bacterial samples from palms that had never touched the mouse. In all nine cases, the bacterial community on each mouse was much more similar to the owner's hand.

The team sampled private and public computers at CU-Boulder, as well as hand bacteria collected from a variety of volunteers on campus. The study showed the new technique is about 70 to 90 percent accurate, a percentage that likely will rise as the technology becomes more sophisticated.

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