New Science for the Murder Victim Search

Vass proposes a molecular-signature approach to the problem. If he can identify a set of human-decay chemicals that changes in a predictable way over the days, months and years after death, time-stamping a murder will become a matter of running a vapor sample through the kind of analytical equipment found in any forensic lab.

In the short term, Vass pursues a simpler goal. A not-to-be-named federal agency funds his study because it wants a gadget to sniff out clandestine graves. There is, of course, an analogue in nature for this electronic body sniffer: the hound. ?We already know that cadaver-searching dogs can do it,? Vass says. ?They?re probably homing in on just one or two key molecules seeping out of the ground.?

Like humans, however, dogs have bad days. They get tired and distracted. They suffer the occasional cold. Training a cadaver dog and maintaining its skills with regular workouts is tricky, given the nature of the scent in question.

Vass believes the technology is at hand to build a hard-wired grave sniffer -- just as soon as he can isolate the chemical targets for its electronic nose. This is what I?ve come to see, so Vass unlocks the farm gates and leads me past a half-dozen moldering corpses to a red-clay knoll where ?02-25,? a middle-aged stroke victim, lies 2 feet under.

Seven months ago, Vass slipped 02-25 into the ground clad in jockey shorts and partially wrapped in a sheet. ?Most murder victims get carried to the hole inside something. A blanket, garbage bag, you get the idea.? The shallow grave is also typical. ?Statistically, few killers dig deeper,? says Vass.

This grave site?s only significant departure from a conventional crime scene is that 02-25?s grave has some elaborate plumbing. A network of slender, perforated pipes -- a French drain of sorts -- runs above and below the remains, collecting the vapors generated as millions, possibly billions, of bacteria degrade and recycle the soft tissues and bones. To one side of 02-25, the pipes make a 90-degree turn, emerging from the ground as three sampling ports.

To each, Vass attaches a ?triple-sorbent? trap -- a small metal cylinder packed with three grades of carbon granules for collecting light, medium-weight and jumbo-size molecules. As he has done more than 30 times in the past seven months, Vass pulls the subterranean vapors up through the sampling ports and into the carbon traps with the help of a portable generator. Later, he?ll take an overnight sample of the gases that are collecting under a stainless-steel hood placed over the grave.