Germs may blow the whistle on crooks one day

Bacteria on people's hands are highly personal to each individual
Image: Swabbing a keyboard
Researchers have developed a new technique to identify individuals by the communities of hand bacteria they leave behind on objects they have handled, such as computer keyboards.Warning to criminals: Rubbing out your fingerprints may no longer be enough. Your germs could still give you away.

It turns out the colonies of bacteria that live on people's hands are highly personal to each individual.

That means forensic experts could one day use those bacteria to prove who had touched an object, researchers report in Tuesday's edition of Proceedings of the National Academy of Sciences."Each one of us leaves a unique trail of bugs behind as we travel through our daily lives. 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," lead author Noah Fierer of the University of Colorado said in a statement.

In one test the researchers swabbed computer mice that had not been used in 12 hours and compared the bacteria with those collected from the hands of the computer owner and 270 other randomly chosen people. The closest match was to the computer owner.

Overall, the researchers said, their technique was between 70 percent and 90 percent accurate. Researchers said that's expected to improve as the technique becomes more sophisticated.

This analysis is something that scientists couldn't have done even two years ago, noted Fierer, an assistant professor in Colorado's ecology and evolutionary biology department.

In addition to smudged fingerprints, the technique may also be useful in determining who has touched things like fabrics and highly textured materials, the researchers said.

The average human hand contains about 150 species of bacteria with only about 13 percent shared by any two people, Fierer's team found in earlier studies.

The new research was funded by the National Science Foundation, the National Institutes of Health, the Crohn's and Colitis Foundation of America and the Howard Hughes Medical Institute.