Bugs discovery could help police pinpoint time of death

DEATH microbes which cause the human body to rot have been identified by scientists in a breakthrough that could help police pinpoint the time of death in crime scenes.

Although crime dramas on television often show pathologists accurately predicting a time of death, it is actually notoriously tricky to estimate once rigor mortis has subsided, which happens within about 24 hours.

To find out if changes in the body could help, the American National Institute of Justice (NIJ) funded a study in which 36 human corpses were allowed to decompose in different climates and seasons in the United States.

Scientists from the University of Colorado then took skin and soil samples over a 21-day period and found that about 20 species of bacteria and fungi turned up “like clockwork” at certain times in the process.

Microbes present included the bacterium, acinetobacter which causes urinary infections and pneumonia, and wohlfahrtiimonas which is responsible for blood infections.

The team believe that the bugs are being brought via insects which infest the body after death, rather than coming from the gut of the dead person.

“It’s really cool that there are these microbes that always show up to decompose remains,” said Prof Jessica Metcalf, of Colorado University, the senior author on the study. “We see similar microbes arrive at similar times during decomposition, regardless of any number of outdoor variables. The waves of microbes are clock-like.”

Researchers believe that in future, police will be able to sample the microbiome of a crime scene to gauge how long a dead body has been at the location.

The team discovered that the same set of about 20 species were present regardless of the type of soil or climate, suggesting they play a universal role in decomposition.

Experts have also built a computer program that can determine the time of death by looking at the quantities of the species, which ebb and flow.

Prof David Carter, of Chaminade University in Honolulu, who helped develop the program, said: “You never know if there will be fingerprints, or bloodstains or camera footage. But the microbes will always be there.”

The research was published in the journal