Scientists crack mystery that could solve murder

Scientists crack mystery that could solve murder

In a major breakthrough, scientists have identified a group of microbes found in dead bodies at specific points during decomposition, making it much easier to calculate a time of death.

The bodies were studied as they decomposed in different environments, with scientists discovering a network of 20 different microbes present throughout the bodies, appearing like clockwork at certain stages of the decomposition process, according to a new paper in the journal. Nature Microbiology.

This could be used to determine the time of death of bodies in homicide investigations, scientists hope, significantly aiding efforts to solve murders.

“It’s really interesting that there are these microbes that always show up to decompose animal waste,” paper author Jessica Metcalf, an associate professor of microbiology and ecology at Colorado State University, said in a statement. “Hopefully, we’re opening up this whole new area of ‚Äč‚Äčecological research.”

When an animal or other living thing dies, it begins to decompose, with its organic materials digested and returned to the food chain. There are several stages of decomposition of the human body: fresh, swollen, active, advanced and dry decay.

forensic investigation
Image in the state of a crime scene investigation. Scientists have discovered microbes found in all dead bodies in the process of decomposition.


As the cells begin to digest themselves, internal organs begin to swell due to the gas released by the bacteria, and insects begin to lay eggs in the softer parts of the body. These larvae eventually hatch as maggots and devour more of the soft tissue.

For a recent death, the time of death is determined using body temperature and what stage of severity of death the body entered, while bodies that have been dead longer are judged based on the stage of decomposition. However, the rate at which the body cools, or the rate at which decomposition begins, depends on the surrounding environment.

“The onset of acute death is usually 2-4 hours after death, and severity lasts 36-72 hours after death,” said Mark Evely, director of the mortuary science program at Wayne State University, who was not involved in the study. said Newsweek. “The rate at which a dead body cools depends on factors within the body itself, such as body mass and current disease processes, and environmental conditions, such as air temperature, whether the body is in water, etc.”

This study examined 36 corpses in several facilities, measuring how their microbiomes changed during the course of decomposition in different climates and seasons of the year. The researchers found that regardless of climate and soil type, there was the same set of 20 microbes found in all 36 bodies. These microbes were also found to arrive simultaneously throughout the bodies.

“We see that similar microbes arrive at similar times during decomposition, regardless of any number of external variables you can think of,” Metcalf said.

This discovery has huge implications for forensic science, as these microbes can be used to help determine more precisely how long a body has been dead. In fact, using data from the study, the authors created a machine learning tool that can predict time since death based on the microbiome.

“When you’re talking about investigating death scenes, there are very few types of physical evidence that you can guarantee will be present at every scene,” said paper co-author David Carter, a professor of forensic science at the University Chaminade in Honolulu. Statement. “You never know if there will be fingerprints, bloodstains or camera footage. But the germs will always be there.”

bacteria in the petri dish
Image of a petri dish with growing bacteria. Scientists found a group of microbes found in dead bodies.


This will be particularly useful for bodies found outdoors, as there is less data on the time of death after exposure to the elements.

“We are talking about death scenes in nature,” he said. “It can be difficult to gather information in those types of investigations,” Carter said.

Furthermore, these microbes appear to be brought into the body by insects arriving to feed on the bodies and lay their eggs.

“It looks like the bugs are bringing the germs in,” Metcalf said.

The researchers hope that these findings can be used not only to aid in forensic investigations, but also throughout microbial ecology research and agriculture.

“I see many potential applications in agriculture and the food industry,” Metcalf said. “I feel like we’re breaking ground on basic ecology and nutrient cycling.”

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