The US Department of Justice funds the decomposition of 36 corpses, culminating in the ‘arrival’ of microorganisms in all of them, allowing the date of death to be accurately determined.
They are not in our body. Nor in the environment around us, but when we die, they appear suddenly. Twenty microorganisms have revolutionized forensic investigation Taking a major step forward is determining one of the main clues to solving a crime: the time of death, which will help identify bodies, rule out suspects, or disintermediate them based on time or calendar date.
Despite what we see in television series, the first thing that forensic experts make clear is that it is not possible to determine the time of death. We can get closer to solving the case, and even apply methods that sometimes prove counterproductive. that’s why he US Department of Justice It was decided to fund an investigation that included the decomposition of 36 corpses turned over to science at three forensic anthropological facilities: the University of Tennessee at Knoxville; Sam Houston State University; and Colorado Mesa University.
There they managed to identify what looks like a network of about 20 microbes They inspire universal disapproval of animal meat under any circumstances. “It’s amazing that these microbes exist because we’re opening up a new area of ecological research,” says Jessica Metcalf, an associate professor in the Department of Animal Sciences at Colorado State University and responsible for the research published in Nature. Microbiology.
Decomposition of dead organic material is one of the fundamental processes on Earth. Organic plant waste represents the majority of decomposing matter, and is relatively well understood. However, Until now, little was known about the ecology of vertebrate decomposition., despite its potential to advance forensic science, including our own decompositions. Unlike plants, animal corpses are rich in easily degradable proteins and lipids, but their effects on biogeochemistry and ecology are barely known.
The research involved observing the decomposition of carcasses in laboratories in different climates during four seasons and collecting them 21 days later skin and soil samples From each of them.
Metcalf and his colleagues collected a wealth of molecular and genomic information, which they used to create an overview of the “microbial community” or microbiome present at each site. “Essentially,” Metcalfe explains, “what microbes are there, how did they get there, how have they changed over time, and what are they doing.”
Surprisingly, he explains, and regardless of climate or soil type, The 36 dead bodies contained the same 20 microbes that were experts in decomposing dead bodies., Moreover, “they arrived like clockwork at the same points in all the bodies, regardless of all the external variables you can imagine,” Metcalfe said.
In addition to identifying these universal decomposers, the team also tried to determine where this microbial community came from, as they are neither in soil, nor in the catalog of the skin microbiome, nor in human intestines, which Play a fundamental role. Disintegration of living beings. ,It seems that it is the insects that bring these“, Metcalf says, in the absence of more data. All the bacterial decomposers discovered were found in the Calciphoridae, known as blowflies.
Using machine learning techniques that combined the new data with previous work, Metcalf and his colleagues (David Carter, professor of forensic science at Chaminade University in Honolulu, and Rob Knight, director of the Center for Microbiome Innovation at the University of California San Diego ) , created A device that can accurately predict the time after death of a body Also known as postmortem interval.
“When investigating a crime scene, there is very little physical evidence that can be guaranteed to be present at every one,” explains Carter. ,You never know if there will be fingerprints, blood stains or security camera footage “But we now know that these germs will always be there, and we’re talking about outdoor death scenes, where information can be very difficult to gather.”
Nancy LaVigne, director of the National Institute of Justice, called the research particularly promising. “A key question in any death investigation is ‘When did this person die?’ Predicting time of death helps identify the deceased, determine suspects, and corroborate or refute evidence elsewhere.”
These findings are the result of more than a decade of work by Metcalfe, Carter and Knight, including a preliminary study that involved decomposing rats and four other human cadavers in various soils in a controlled laboratory at Sam Houston.
Beyond forensic applications, Metcalf sees other opportunities for these microbes. “I see potential applications in agriculture and food industry” said the researcher, who intends to expand his research in this area, including studying possible differences in the microbial ecology of large and small vertebrates. “I think we will break new ground in basic ecology and nutrient cycling. Are breaking.”, explain.