Scientists have found a new way to track down criminals - using the unique collections of bacteria they leave behind on things they touch.
The human body is plastered in a highly diverse community of bacteria that form a microbial fingerprint unique to each individual. So much so in fact that, even after a scrub with soap, after a few hours the same bugs are back on the average pair of hands.
Now researchers have shown that this bacterial badge could even be used forensically. Writing in the journal PNAS, University of Boulder Colorado scientist Noah Fierer and his colleagues took swabs from computer mice and keyboards and were able to produce a genetic profile of the bacteria present and then pick out correctly - from more than 250 possible pairs of hands - the computer owner.
Although they caution that further investigation and validation of the technique will be necessary to establish its forensic credentials, the researchers think that it could be a powerful adjunct to existing methods. "This approach might represent a valuable alternative to more standard techniques," they point out.
"Given the abundance of bacterial cells on the skin surface and on shed epidermal cells, it may be easier to recover bacterial DNA than human DNA from touched surfaces."