The definite time of deaths can be now analysed with definite accuracy, scientists have said.
According to a new study forensic scientists can determine the exact time of death in cases involving human corpses with the help of a ‘microbial clock’. The researchers say, the clock is essentially the lock-step succession of bacterial changes that occur during postmortem as bodies move through the decay process.
Jessica Metcalf, first author of the study from University of Colorado Boulder, said that the previous studies on the human microbiome indicate there is good reason to believe similar microbial clocks are ticking away on human corpses.
“Our results provide a detailed understanding of the bacterial changes that occur as mouse corpses decompose, and we believe this method has the potential to be a complementary forensic tool for estimating time of death in human,” said Metcalf.
Scientists say, the more days that elapse following a person’s demise, the more difficult it becomes to determine the time of death with any significant accuracy.
For the study, the researchers tracked microbial changes on the heads, torsos, body cavities and associated grave soil of 40 mice. The analysis was done at eight different time points over the 48-day study. The scientists used high-technology gene sequencing techniques on both bacteria and microbial eukaryotic organisms like fungi, nematodes and amoeba postmortem.
Elaborating upon the process, Chaminade University forensic scientist David Carter, a co-author on the study, said, “The stages after death include the “fresh” stage before decomposition, followed by “active decay” that includes bloating and subsequent body cavity rupture, followed by “advanced decay.”
“At each time point that we sampled, we saw similar microbiome patterns on the individual mice and similar biochemical changes in the grave soil,” said Laura Parfrey, a faculty member at the University of British Columbia who is a microbial and eukaryotic expert.
“And although there were dramatic changes in the abundance and distribution of bacteria over the course of the study, we saw a surprising amount of consistency between individual mice microbes between the time points – something we were hoping for,” said Parfrey.
The study was published in the journal eLIFE.