By Clay Dillow Posted 03.16.2010 at 10:58 am 5 Comments

Your Hands Swimming with potentially damning bacterial evidence. woodley wonderworks

The cats over at CSI might just have another forensic tool to supplement their super-sleek glass and steel science lab: the bacteria on our hands. A group of researchers at University of Colorado Boulder have conducted a proof-of-concept study in which they were able to accurately identify people using samples of bacteria collected from their computer keyboards and mouses.

As it turns out, even the most obsessive-compulsive among us carry about 150 species of bacteria around on our hands, and those bacteria in turn carry a genome unique to that person. Those bacteria could potentially become a damning forensic tool at crime scenes, allowing investigators to gather DNA information unique to a perpetrator even without recovering any of that person's actual DNA.

But aspiring villains need not worry about being bacterially identified anytime soon. As is, the process is only 70-90 percent accurate, a margin of error too wide for even the most kangaroo courts. There are still a lot of questions to be answered as well: if more than one person has touched a piece of evidence, will the microbial profile be compromised? Is the microbiome stable enough to be used as an identifier (since, for instance, taking antibiotics can alter one's bacterial profile)? Can criminals intentionally alter their bacterial profiles to throw investigators off the trail?

Related Articles

Booby-trapping bacteria
A Material Based on Sharkskin Stops Bacterial Breakouts
Genetically Engineered Bacteria Etch Famous Faces Into a Petri Dish

Tags

Science, Clay Dillow, bacteria, bacterial DNA, crime scene investigation, csi, forensics, health, microbiome
But these very "flaws" also give the bacterial profile a kind of complexity that DNA alone simply cannot match. For instance, smudged fingerprints can't be accurately used for identification, but they can be mined for bacterial data (a swab of the skin provides 100 times more microbial DNA than human DNA). And the mircrobiome offers clues that DNA alone cannot, like where a person lives and works or what he or she eats. Even identical twins that share a DNA profile have significantly different bacterial profiles, giving investigators another way to differentiate suspects if not to ID them outright.

There's still a lot of work to be done clearly (like tightening up that 10-30 percent margin of error) but in the meantime the procedure could certainly serve as one more tool in the forensic toolbox even if the evidence isn't courtroom-admissible. Besides, once you have the right guy, it's only a matter of sitting him down and telling him the jig is up; after that, the confession is imminent. At least that's how it works on CSI.

[BBC, Technology Review]

5 Comments

Link to this comment
tmarti69
03/18/10 at 6:46 am

No comment, no comment yet? This would have made capturing the green river killer years earlier, and saved many lives. Using probable cause, a swab from a steering wheel would have narrowed him out of the suspects. The fact that its only 70-90 percent accurate could ease privacy rights of taking samples along with finger prints. If that didn’t work naming a person of interest would mean reporters, or the curious could take samples independently. Since, this would be as easy or easer to obtain than a finger print it’s hard to argue or maintain a privacy right to it.

Link to this comment
wpmcg
03/19/10 at 12:40 am

it seems to me that a persons bacterial profile would naturally change over time, being influenced by changes in their environment and relationships. i would think that pairing a profile from a crime scene to a suspect could only be done within a short period of time. if that is the case, then this process could never be used in court as any lawyer could argue that "my client may have previously come in contact with the perpetrator". a stupid argument that does not address the science behind the profiling, but try disproving it. still, think of the potential of using this to get an idea where to search for abductors or kidnappers. that alone could make this an invaluable tool.

Link to this comment
zsingerb
03/19/10 at 6:43 am

So now, I can shake hands with you wearing gloves, claim I have a cold, and then put the bacteria that you had on your hands into the scene of the crime.....

Link to this comment
twobrain
03/19/10 at 6:21 pm

@ zsingerb I agree with that thought line. How bout a shared office with those cold/flu sharing keyboards. My coworker goes to work uses my keyboard picks up some mixed bacteria from me and or other users of the same work station. Then we all become suspects because they don't wash there hands.
Part of the problem is that juries the word over really don't understand the tech involved in forensics so they just take whatever the "expert" says as gospel. Condemning anyone without a second thought.

Link to this comment
king.of.losers
04/08/10 at 8:50 am

ahh my greatest friends are in the end my greatest enemys all shall sherch for the closest ultra violet bath room sink so I my kill off my betrayers. wait one second
All hail king of the losers BUHAHAHAHAHAHA!


138 years of Popular Science at your fingertips.

Innovation Challenges

Make your ideas part of the revolution
Learn morePowered by Innocentive



Popular Science+ For iPad

Each issue has been completely reimagined for your iPad. See our amazing new vision for magazines that goes far beyond the printed page



Download Our App

Stay up to date on the latest news of the future of science and technology from your iPhone or Android phone with full articles, images and offline viewing



Follow Us On Twitter

Featuring every article from the magazine and website, plus links from around the Web. Also see our PopSci DIY feed


February 2012: The Future of Fun

Science is reinventing play, from extreme sports to gamification to ridiculous roller coasters to the playgrounds of tomorrow, and this issue is chock full of fun. Also, on a less fun note: Did global warming destroy my hometown?


circ-top-header.gif
circ-cover.gif
bmxmag-ps