Research has identified a network of microbes – bacteria and fungi – which are responsible for the decomposition of bodies. They act in a predictable way which will allow crime scene investigators (CSI) in conjunction with pathologist to accurately ascertain the time of death and in doing so assist the investigation.
The research found that scientists were able to time the moment of death after a body had been outside for several weeks to a window of a few days, which is an improvement over traditional forensic methods.
RELATED: Using bacteria to detect unexploded landmines
New area of ecological research
Professor Jessica Metcalf of the department of animal sciences at Colorado State University, the lead author on the study, which is published in Nature Biology said that, “It’s really cool that there are these microbes that always show up to decompose animal remains. Hopefully we are busting open this whole new area of ecological research.”
Although we know a lot about the decomposition of dead biological matter, comparatively little is known about the decomposition of vertebrate animals including of course the human as reported by Rhys Blakely the science correspondent of The Times, the source of this article.
The study
In the study they assessed 36 bodies donated to science. They were left to decompose outside at research facilities in America. Specifically at the University of Texas, Knoxville, Sam Houston State University and Colorado Mesa University.
The bodies were exposed to different seasonal climates.
They collected soil and skin samples over the three weeks of decomposition.
In this way, having taken samples, they were able to build a picture of the micro-microbial community present on the bodies. The Professor said that it showed “what microbes are there, how they get there, how does that change over time and what are they doing.”
The same group of 20 specialist decomposing microbes were always present no matter the soil type or climate.
Microbes act like clockwork
It is said that the microbes arrived “like clockwork” at certain points in time throughout the decomposition. The Professor added that “we see similar microbes arrive at similar times during decomposition, regardless of any number of outdoor variables you can think of.”
They used statistical techniques (machine learning) to create a tool which can accurately predict the time of death of a person which is known as the “post-mortem interval”.
The Professor of forensic sciences at Chaminade and University of Honolulu, David Carter, said: “When you’re talking about investigating death scenes, there are very few types of physical evidence you can guarantee will be present at everyone. You never know if there will be fingerprints, or bloodstains, or camera footage. But the microbes will always be there.”
He added that it can be difficult to gather information at outdoor death scenes.
Time of death vital to investigation
The research was funded by the National Institute of Justice, the director of which, Nancy La Vigne, said: “One of the principal questions of any death investigation is ‘When did this person die?'”
RELATED: Bacteria finds a way to help recycle plastics
