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Rotting pig carcasses crawling with maggots are probably not the most appealing of study subjects for the average graduate student. And when Sarah Jones first faced the prospect of working with them, she didn't know how she would handle the sight, the smell, and all the vermin. But as she worked on her project—profiling the chemical signature of death in decaying pig cadavers—it became far more interesting than she had imagined, and slightly less repulsive. "The smell wasn't great, but I always had my mask on," she says.
Jones, a master's candidate in forensic science at The Pennsylvania State University, is motivated by the knowledge that her dirty work could one day aid in the recovery of earthquake and natural disaster victims as well as the discovery of mass graves and clandestine (body disposal) sites. A portable chemical-detection device based on her profiling also could someday help investigators in the field quickly determine just how many days—or weeks—had passed since a victim's death. All of this, she says, makes "watching a pig decaying in front of my eyes" more tolerable.
Cats and dogs have often acted as living detectors of death. Oscar, a cat, follows the smell of death to be by the side of terminal patients at a Rhode Island hospice, as featured in a 2007 issue of The New England Journal of Medicine. And trained dogs continue to help investigators in the search for dead bodies. But, Jones notes, "we don’t know how much they smell, or what they smell." A portable device could ultimately help pinpoint these chemicals, and the time elapsed from death, "more concretely," she says.
The first step in developing such a technology is to catalogue the detectable scents associated with dead bodies. Previous studies of death's chemistry have relied on decomposing human bodies, which allow "no control over how or when they died," Jones explains. And without that information, a full profile of the putrefactive process is impossible to produce; chemicals that are called putrescine and cadaverine, for example, are released very early on and have therefore been nearly undetectable. But she found the solution in swine.
"We wanted to try to simulate a human body as close as we could," says Jones, who is collaborating on the project with Dan Sykes, a chemistry professor at Penn State. Pigs are comparable in size with humans and "go through basically the same stages of decomposition as us," she says.
The project's pigs were humanely euthanized in a way that simulated the circumstances of a human death from an open gunshot wound. The fresh bodies were then placed in varying levels of enclosure on a remote field near the Penn State campus. Three times a day over the course of a week Jones would collect and replace polyacrylate fibers suspended above the carcass to absorb the released chemicals. Then she'd carry the fiber—on ice to keep the chemicals from being released—to the lab for analysis.
"We've been able to develop a consistent profile with early stages of decomposition," says Jones, who presented the project's preliminary results at the American Chemical Society meeting yesterday in Washington, D.C.
Jones and Sykes have also found some interesting surprises in the decomposing flesh. Environmental conditions, including humidity and rain, profoundly affect the profiles of the more than 30 compounds released during decomposition. Nevertheless, the comings and goings of bugs appear highly predictable. "On day three, the maggots are there like clockwork," Jones says. She and her colleague have found significant correlations between when the bugs arrive and the concentrations of certain compounds, including that "blowflies are attracted to putrescine," she says. (The Penn State entomology department is actually creating their own forensic database of insects.)
There's far more pig decomposition smelling to be done, as Jones notes the research is still in its early stages. So, although future emergency responders and crime scene investigators may carry a pocket-size death detector, for now Jones continues her own grisly work—at least until she passes on her mask to the next brave graduate student.
