Crime scene investigators could soon be using bacteria and fungi to solve complex murder cases.

Research has found that certain microbes are extremely reliable indicators for determining the precise time of death, because they appear at different stages of the decomposition process.

These microscopic clues – which reach bodies on the backs of insects – could help police investigators establish a timeline for the crime when other evidence is unavailable.

Professor David Carter from the Chaminade University of Honolulu, a co-researcher on the study, said: “When you’re talking about investigating death scenes, there are very few types of physical evidence you can guarantee will be present at every scene.

“You never know if there will be fingerprints, or bloodstains or camera footage. But the microbes will always be there.”

A research team led by scientists from the University of Colorado observed the decaying remains of 36 humans bodies for 21 days.

The team found that, regardless of climate or soil type, the same 20 microbes were present. These micro-organisms, including different and bacteria fungi, arrived like clockwork at certain points throughout the observation period.

“We see similar microbes arrive at similar times during decomposition, regardless of any number of outdoor variables you can think of,” said Jessica Metcalf, of the University of Colorado

Experts in the UK and the US suggested that microbes could one day become a new tool in the CSI armory.

“If further research confirms the findings, and if this form of analysis can be done rapidly and cost effectively, it would be a valuable additional tool for UK police investigations,” said Professor Ruth Morgan, director of the UCL Centre for the Forensic Sciences.

“Being able to establish a post-mortem interval has remained a really challenging issue in forensic science. The findings from this study are a really exciting development, particularly given the prevalence of microbes at these kinds of crime scenes.

“If we can get a more transparent and reproducible estimate of the time since death, that is really valuable intelligence that can help to narrow the time frame of interest, focus the lines of inquiry – and that increases the possibility of solving the case,” she said.

Nancy La Vigne, director of the National Institute of Justice in the US, which funded the research, added: “One of the principal questions of any death investigation is ‘when did this person die?’”

“This shows promising results for predicting time of death of human remains, aiding in identification of the decedent, determining potential suspects and confirmation or refutation of alibis.”

The study is published in the journal Nature Microbiology.