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Forensic Scientists May Be Able to Catch Criminals With The Germs They Leave Behind



Even the sneakiest of burglars may have a hard time escaping the law with a forensic technique that involves analyzing the unique "microbial signature" we leave in our wake. This is part of a National Institute of Justice funded project involving a team of microbiologists and forensic experts, which was presented at the ASM Microbe conference in Atlanta, Georgia. 

The research builds on previous studies that have found that people's homes – and even their shoes – contain a personalized microbial cocktail that can be used to confirm their identity. This so-called microbial signature can pass onto objects (say, a cell phone) and surfaces (perhaps a desk in the house you broke into). They are invisible and made up of the millions of bacteria and other living things we shed from our skin and our nostrils on a constant basis. Want to know a gross fact? We cast off 36 million microbial cells every single hour.


Now, researchers have tested the potential of using these signatures in a forensic setting using a series of mock crime scenes to see whether or not they can catch the culprit with just their discarded bacteria – and they can with a 70 percent accuracy.

Ten "crime scenes" were staged in homes in Fort Lauderdale, Florida, and Chicago, Illinois, involving 45 undergraduate students pretending to be burglars. The team noticed a stark difference in the microbial composition in the homes before and after the "crime" had taken place.

By studying the microbes from the nostrils and skin from every "burglar", they were able to sort different sets of microbes into signatures (or fingerprints) that were unique to each and every individual. These personalized microbial cocktails allowed them to single out the burglar from the group with incredible, if not perfect, accuracy. 

“DNA will always be the gold standard – that’s never going to change,”  Jarrad Hampton-Marcell from the Argonne National Laboratory in Illinois, who led the research, told The Independent.


“But what lawyers try to do is put together a picture – maybe if DNA isn’t left behind or fingerprints are smudged, there is a good chance you’re going to leave behind this trace evidence. Then potentially we could use this as a forensic tool.”

Right now, the research is in the very early stages. The team still have to work out how long a burglar's microbial signature will persist at the crime scene, as it starts to decay within half an hour of being removed. They also hope to boost the accuracy of the analysis to 90 percent or higher.

So don't expect your local DI to be analyzing discarded bacteria any time soon. 


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  • bacteria,

  • microbes,

  • forensics,

  • microbial signature,

  • crime scene,

  • burglary