Perth body farm study on piglets' decomposition to help forensic scientists analyse crime scenes

Jun 03, 2023

When police find a decomposed body, the clothing that person was wearing could hold the key to finding out how they died.

Warning: This story contains an image some readers may find distressing.

Damage to the fabric could suggest a bullet hole or a cut from a knife, but a group of Perth scientists is investigating if insects and the natural environment could cause similar damage to the clothing.

Paola Magni, a senior lecturer in forensic science at Murdoch University, said understanding the difference between marks caused by weapons, compared with those caused by decomposition, was crucial to avoid misinterpretation of evidence that could have grave consequences.

"After 50 days of the composition process, does the tear look like a cut, does the cut look like a tear?" Dr Magni said.

"Or do plain fabrics look like they had been cut or torn apart?

"That's something that in a real investigation could create a big question in a court of law and possibly a miscarriage of justice."

Dr Magni and her team studied the bodies of 100 decomposing stillborn piglets wrapped in fabric at a body farm the university owns.

She said the accuracy of forensic textile analysis was important because stabbing injuries were the leading cause of homicide in Australia and other countries with limited access to firearms.

She said ripped, torn or stretched clothing was also used as evidence in sexual assault cases.

The experiment was carried out in bushland during WA's hot summer, with the stillborn piglets wrapped in a variety of common fabrics.

Dr Magni said her team was surprised by what they saw during the study.

Ruby Dixon says it's the pervasiveness of sexual assault that drives her to find new ways of gathering evidence to hold perpetrators accountable.

"We didn't expect how much the stretch was going to have an impact on the change of the structure or the damage [to the fabric]," she said.

"We didn't expect that insects were going to be very interested in certain parts of the fabric … for example the interface between the dead body and the soil."

She said the insects caused damage to the fabric as they moved in and out of the body.

"That can be very important in court because sometimes the question is about what happened to that fabric," Dr Magni said.

"It doesn't mean that there is a shotgun or there is a cut."

Dr Magni said she hoped to repeat the study in winter and in a different landscape, such as a more coastal area.