For the past five years, Arpad had been collecting and analyzing the gases given off by bodies as they decomposed. In one corner of the Body Farm, he’d buried four bodies in graves of varying depths. He threaded the graves with a grid of perforated pipes leading to the surface of the ground. Every two weeks since burying the bodies, he had collected air samples from within and above the graves, and had run the samples through a gas chromatograph — mass spectrometer, a sophisticated analytical instrument that isolated individual compounds from the smelly samples. Over the course of the experiment, Arpad had identified nearly five hundred separate compounds given off by bodies as they decay. Many of the compounds were common, found virtually everywhere in nature; however, he’d found about thirty key compounds that — collectively — could be read as the fingerprint of a buried body. More specifically, as the fingerprint of a buried human body, rather than as the rotting remains of, say, a deer or dog or pig.
But Arpad wasn’t just analyzing the chemical fingerprint of a buried body; he was also developing a gizmo that could detect that fingerprint out in the field. The gizmo, which he called “the sniffer,” was a mechanical version of a cadaver dog’s nose, and it was designed to find clandestine graves. The last time I’d seen him, Arpad was testing a prototype of the sniffer.
After shaking hands with Arpad, Thornton closed the door to the office. Arpad — a dark-haired, brown-eyed man of Hungarian descent — raised his eyebrows in an unspoken question. At Thornton’s request, I hadn’t told Arpad what we wanted to see him about; only that an FBI agent and I wanted to consult him about a forensic case.
“This is fairly sensitive,” said Thornton. “We have evidence that a murder occurred in the vicinity of the Laboratory back during the Manhattan Project. We also suspect that espionage — spying for the Soviets — may have played some part in the murder.”
“Interesting,” said Arpad. “What’s the evidence?”
Thornton nodded at me. I opened the manila envelope I’d brought with me and slid out the photographs, laying them on Arpad’s desk. As he studied the images of the body and the shallow grave, he smiled. “That looks like pretty good evidence,” he said. “This evidence has just come to light?” I nodded. “This body was never found?” I nodded again.
Arpad smiled again. “Very interesting,” he said.
“Tell me about this sniffer you’re working on,” Thornton said. “How does it work — and how well does it work?”
If I hadn’t known Arpad well, I probably wouldn’t have noticed the flicker of impatience in his eyes. It lasted only a split second, and then — almost like flipping a switch — he was in presentation mode, pitching himself and his work to the agent. “The research is funded by the Department of Justice,” he said. “We’ve been exploring two technologies for detecting clandestine graves. One is a simple off-the-shelf technology; the other is something more sophisticated, which we’re creating from scratch for DOJ.” He walked around the desk and picked up a pistol-shaped device from a bookshelf that lined the long wall of the office. In the place of a metal barrel, though, was an eighteen-inch black rubber tube, with a metal tip on the end. “This is a TopGun H10X commercial Freon detector,” Arpad said, “just like air-conditioning technicians use to check your central air for leaks.” Thornton looked puzzled, and I was pretty sure I did, too, as I hadn’t heard this part of Arpad’s pitch before. “It turns out,” Arpad went on, “that among the thirty key compounds a decaying body gives off, three are Freon compounds. So this is an easy way to do a crude search with existing, cheap technology. Here, I’ll show you.” Arpad opened up a file cabinet and removed a small glass vial sealed with a rubber stopper. Inside was about a teaspoonful of something that looked like garden-variety dirt.
“This is a soil sample from the surface of a shallow grave at the Body Farm,” he said. He pried out the stopper; I sniffed, but I didn’t smell decomp. “If the body had been on top of this, this would really stink,” he said, and I nodded in agreement. “But since it was above the body, the volatile fatty acids weren’t soaking into the dirt. Instead, as the bodies underneath off-gased, the gases slowly migrated up through the soil. Much, much fainter.” He dug around in the file drawer and found a plastic bag, then laid the vial in the bottom of the bag. Next he flipped a switch on the detector. It growled to life, with a noise somewhere between a squeal and electronic static. Arpad dialed a switch and the noise subsided to an occasional chirp. Inserting the end of the Freon detector’s wand in the bag, he clutched the bag tightly around the tube to seal it. After a few seconds, the detector began to chirp faster and faster, until soon it was almost back to a continuous squeal.
Thornton nodded, but there was a grudging quality to the nod. “So as long as somebody bags the body for you and you stick that wand in the bag, you can find the body?” This time anyone could have detected the impatience in Arpad’s expression.
“That’s about thirty grams of soil,” Arpad said. “An ounce. There’s probably a few picograms — a few billionths of an ounce — of decomp chemicals in that sample. This isn’t infallible, but it’s not bad for starters, considering that you can buy it on eBay for eighty bucks.”
“So that’s not the sniffer you’re creating for DOJ, right?”
“Right. This is the sniffer we’re creating for DOJ.” Arpad opened a cabinet and removed an instrument that appeared to be a cross between a metal detector and a weed whacker. On closer inspection, I noticed that instead of a loop or a cutting head, the lower end of the device held a small cylindrical probe. Arpad flipped a switch at the upper end of the device, and it clicked slowly, much like a Geiger counter. “Depending on which sensors we put in the probe,” he said, “we can search for a fresh body, a decaying body, or a really old one.” He inserted the probe into the bag, and after a few seconds the clicks ran together into a machine-gun-fire buzz.
Thornton leaned forward and studied the sniffer. “So how long would it take to search an area with that rig?”
“Depends on how big the area is,” said Arpad. “These photos seem to indicate the general location, but we could still be talking about an area a hundred yards square. If you tried to put the probe into the ground every square foot, you’d be taking eight hundred thousand samples. You got months to spend poking the tip of this into the ground?”
Thornton shrugged. “If that’s what it takes. We’ve spent years looking for Jimmy Hoffa.”
“Well, I don’t have years,” said Arpad. “I don’t even have a week, because my DOJ sponsors are breathing down my neck to lock the design of this thing so they can start getting it into the hands of police departments all around the country.”
“Any suggestions,” I intervened, “on how we might harness this as efficiently as possible?”
“I suggest we bring in a cadaver dog to prescreen the search area, see if there are places he’s interested in. Dogs cover ground faster than we can; a good dog could save us days or weeks of gridwork.”
“I thought the idea behind this was to replace the dog,” said Thornton.
“More like ‘supplement’ the dog,” Arpad said. “Dogs have spent millions of years evolving great noses. They can be trained to pick up tiny, tiny traces of specific scents — bombs, drugs, truffles, tumors, human bones. Not only can they detect it, they can track it, swim upstream — figuratively speaking — to the source of it. Scent isn’t a static, stationary thing; it’s almost got a life of its own, like moving water: it flows, it pools, it sinks, it creeps along underground layers of rock. A good cadaver dog can work his way up that current of scent — a few molecules at a time — till he gets closer and closer to the source. If we bring in a good cadaver dog, we could narrow the search area by ninety percent or more.”