Thursday, 09 May 2013

Insects time-stamp bodies for forensics

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crimescene insectbodies2Prof Dadour says the results showed forensic entomology methods for analysing a corpse found on land could be applied to bodies found in water environments. Image: DavidANALYSING insects within a waterlogged corpse might seem an odd way to gather clues but WA forensic entomologists have found it to be one of the best methods of accurately estimating a time of death.

Conducted by researchers from UWA’s Centre for Forensic Science and the University of Florence, the real-life case study analysed insects and their remnants within deceased bodies located in two Italian wells to accurately estimate a post mortem interval (PMI).

UWA professor and co-author of the study Ian Dadour says although forensic entomology has been widely used over the past three decades to analyse corpses found on land, little to no research has been conducted on bodies discovered in aquatic environments.

“When dealing with bodies the two questions that get asked is how they died and when they died, forensic entomology is all about when,” he says.

“With these studies we wanted to demonstrate that it [forensic entomology] can be useful in these conditions, and that it’s really another tool in the toolbox.”

Because different species of insects colonize corpses at varying stages of decomposition, the researchers of the study analysed various insects and their remnants (puparia) collected from the bodies, and from the water in the wells.

The life stages of the insects were then compared with the stage of decomposition of the corpse(s) and also compared with the entomological fauna found around their respective regions.

This analysis allowed researchers to conclude an accurate PMI of the corpses and whether they had been moved from their original location after death.

Prof Dadour says the results showed forensic entomology methods for analysing a corpse found on land could be applied to bodies found in water environments.

“There are a lot of organisms that live in water environments, like invertebrates that we can also deal with,” he says.

“Crustaceans are really the insects of the sea, and there is even some sort of predictable order of crustaceans that come to a deceased body—some arrive when a body is freshly drowned and some after a long term.”

According to Prof Dadour the use of entomology in forensics has been growing along with other specialised sciences, such as botany and geology, which are also utilised to obtain accurate results.

“Forensic entomology can be the answer, but it isn't always going to be the case, you're not going to find bugs in every situation,” he says.

The study also highlighted the need for correct body-retrieval processes and equipment if entomological and other scientific methods were going to be applied successfully to similar cases.

Notes: The study was co-authored by Dr Paola Magni from the Centre for Forensic Science and Dr Matteo Borrini from the University of Florence’s School of Archeological Heritage.

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