A recent breakthrough by researchers at the Zoological Survey of India (ZSI) could revolutionize forensic science. By cracking the genetic code of blow flies, they have created a powerful new tool for solving murder mysteries. This method, called DNA barcoding, allows investigators to quickly identify the species of blow flies at a crime scene, a key step in accurately determining the Post-Mortem Interval (PMI), or time since death.
The study, published in the international journal PLOS ONE, introduces DNA barcoding as a reliable method to identify blow fly species. Until now, investigators had to wait for maggots to mature into adult flies before confirming their species, often delaying timelines and raising doubts in court.
“This is a game-changer for PMI estimation,” said Dr Dhriti Banerjee, Director of ZSI. “Instead of waiting for flies to mature, investigators can now get a species ID from a single maggot or even eggs within hours. This drastically speeds up investigations and provides more accurate timelines.”
The ZSI team, led by Dr Banerjee and Dr Atanu Naskar, analysed 2,977 blow fly samples collected across West Bengal. By decoding a specific mitochondrial gene region called COI (Cytochrome Oxidase I), known as the “DNA barcode,” they identified 17 distinct blow fly species, each carrying a unique genetic fingerprint.
“Forensic science has traditionally focused on the human body,” explained Dr Naskar. “Our research demonstrates that nature itself offers vital evidence. The fly’s DNA is a language we’ve now learned to interpret.”
The results were validated through four international methods, confirming that each species formed distinct genetic clusters. The study produced the first complete DNA barcode reference library for blow flies in West Bengal.
Researcher Oishik Kar compared the DNA barcode system to an “Aadhaar card for flies,” underscoring its potential for global law enforcement. Once uploaded to international databases, the system could help investigators worldwide track time of death with unprecedented precision.
Beyond forensic application, the study also highlights the biodiversity of the region. “The fly, often overlooked, is now a key that can unlock the truth,” Dr Banerjee emphasised.