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Sheriff's deputies working to conduct mock burglary. (Credit: Jose Lopez, Ph.D. Nova Southeastern University)

The human body emits a staggering 36 million microbes into the outside environment—every single hour. Forensic scientists have looked to this signature as a kind of microscopic trail that may track down suspects, or even reconstruct movements in a crime.

The Burglary Microbiome Project, an ongoing study using mock crime scenes and scientific sampling of homes, residents and intruders, is underway to lay the groundwork for implementing the concept in real life, according to a group of scientists from three colleges.

The initial results were presented by the investigators at the American Society of Microbiology’s annual Microbe meeting in Atlanta earlier this month.

“This study is one of the first to use the microbiome as a forensic tool using unique markers rather than variances in microbial community structure,” said Jarrad Hampton-Marcell, a doctoral candidate at the University of Illinois at Chicago, who presented at the conference.

The researchers, including those from Nova Southeastern University and the University of Chicago, first established baselines of the microbiome in the “crime scenes.”

They started by taking bacterial samples from the noses and hands of the residents, as well as various surfaces within their homes.

Overall, a total of 9,965 unique operational taxonomic units, or OTUs, were identified among 30 people who participated in the experiment.

The baseline established, they then conducted the mock burglaries, in which a suspect entered into the microbiome, dragging their own signature through the domestic environment, according to the researchers.

The invaders’ microbial signature was detected and mapped to the homes at greater than 60 percent accuracy, according to the scientists.

“When observing the change in OTUs over time, appearance/disappearance rates showed no significant difference in the absence or presence of other individuals,” add the researchers, in an American Society of Microbiology statement on the work.

But more work remains to refine the markers, and distinguish further markers to improve the accuracy, they said.

“With further improvement in detection of stable markers, the human microbiome may serve as an additional tool for human profiling and crime scene investigations,” added Hampton-Marcell.

The Burglary Microbiome Project has been underway for several years. The scientists have said they are interested in not only confirming a criminal suspect’s identity, but also providing investigatory leads based on gender, age, lifestyle and other factors the bacterial palette may show.

The first demonstration of the potential identification value of the microbiome in humans came from a 2010 Proceedings of the National Academy of Sciences study which looked at traces from computer keyboards and mice, and matched the signatures to the users of the devices. The microbiome of the mouth and gut have also been a focus of several teams looking to establish post-mortem interval, and other processes of death and decay, in the forensic science context.

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