{"id":123,"date":"2014-02-27T21:16:27","date_gmt":"2014-02-27T21:16:27","guid":{"rendered":"https:\/\/knight-devel.colorado.edu\/wordpress\/?p=123"},"modified":"2025-07-31T12:53:40","modified_gmt":"2025-07-31T19:53:40","slug":"could-detectives-use-microbes-to-solve-murders","status":"publish","type":"post","link":"https:\/\/knightlab.ucsd.edu\/?p=123","title":{"rendered":"Could detectives use microbes to solve murders?"},"content":{"rendered":"

Rob, Jess, and Sybil Bucheli of Sam Houston State University talk to NPR about their forensic work. (September 23, 2013)<\/a><\/span><\/p>\n

In the woods outside Huntsville, Texas, scientists are trying to determine whether they can use the microbes that live on the human body as microscopic witnesses that could help catch criminals.<\/span><\/p>\n

It’s a strange scene at the Southeast Texas Applied Forensic Science Facility<\/a>. At first, it’s easy to miss the human bodies scattered among the tall pines, wild grass and weeds.<\/span><\/p>\n

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Jessica Metcalf, a microbial ecologist at the University of Colorado, says the mapping of changes in bacteria on human remains at the facility in southeastern Texas “is really pushing the envelope of microbial forensic science.”<\/span><\/p>\n<\/div>\n<\/div>\nKatie Hayes Luke for NPR<\/span><\/div>\n<\/div>\n

“We hope microbes can tell crime scene investigators how long a person has been dead,” Sibyl Bucheli<\/a> of Sam Houston State University explains, as she leads a group of researchers and visitors from NPR through a tall, chain-link fence surrounding the facility and down a dusty path to her research plot.<\/span><\/p>\n

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The facility is one of the few places where, in the interest of developing new tools for forensic science, researchers can leave human bodies out in the open to study what happens as the remains decompose.<\/span><\/p>\n

Bucheli is an entomologist who has spent years studying the ways insects on a body can help pinpoint how long a murder victim has been dead. Knowing how long it takes a particular species of fly to complete its life cycle from egg to larva to pupa to winged insect, for example, can help an investigator figure out how long a corpse has been exposed to the insects, establishing a minimum time since death.<\/span><\/p>\n

That got Bucheli thinking. “If insects change through time, then so do bacteria,” she says. “And if insects can be used, so can the bacteria.”<\/span><\/p>\n

It’s possible, she says, that information from bacteria<\/a> could improve the accuracy of these time-of-death estimates. The microbes might also be useful when insects aren’t present, she says, helping to determine how long a person has been dead, when insects aren’t available to do that.<\/span><\/p>\n

Such research is just in the beginning stages, but already, a scientific team at the University of Colorado has been able to use bacteria alone to narrow down how long a mouse has been dead to within three days.<\/span><\/p>\n

“We’re really pushing the envelope of microbial forensic science,” says microbial ecologist Jessica Metcal<\/a>f, a member of that Colorado team. She and her boss, microbiome researcher Rob Knight<\/a>, have come to the forensics facility in southeastern Texas to collaborate with Bucheli, hoping to do with human bodies what they did in the mice<\/a>.<\/span><\/p>\n

One of the first tasks the day we visit is placing three fresh bodies in the woods. A small tractor pulls up, carrying the first body inside a blue plastic body bag. Three men lift the body off the tractor and place it on the ground. They unzip the bag and carefully unwrap the white sheet that swaddles the cadaver.<\/span><\/p>\n

“We want to do this as respectfully as possible,” Bucheli says.<\/span><\/p>\n

It’s a difficult moment. Corpses that have been in the field a little longer look like mummies, barely recognizable as human. The new remains are from people who have only recently died and donated their bodies for scientific research. Bucheli is clearly moved. She pauses briefly for what she calls her “thank-you moment.”<\/span><\/p>\n

“I’m deeply appreciative of the people who make my research possible … all of them,” she says.<\/span><\/p>\n

The scientists mark each body’s position with a metal post and then begin several hours of intense work, meticulously gathering dozens of samples of bacteria.<\/span><\/p>\n

They carefully scrape the skin in the same spots on each body and methodically scoop up dirt from precise locations near the remains. Their plan is to come back day after day, month after month, to sample these exact spots, to figure out if, over time, the communities of bacteria in these various spots change in predictable ways as time passes and the remains decompose.<\/span><\/p>\n

“We’re looking for a microbial clock,” Metcalf says. A clock like that could be used as a reference tool in forensic investigations.<\/span><\/p>\n