“That’s Raccoon Mountain,” he said. “TVA has a big pumped-storage reservoir up there, a lake nearly a mile wide. They pump water from the river up there at night, or whenever there’s not much demand for power. Then, whenever the demand for power ramps way up-hot summer afternoons, cold winter mornings-they draw it down, letting the water spin generating turbines down there by the river.” He pointed down into the gorge, to the shore directly opposite us; several buildings and a parking lot had been set at the base of the steep mountainside, and I saw water churning out a spillway and into the river channel.
“You’re a good tour guide,” I said.
“Not many people have this kind of view from their workplace,” he said. “I eat lunch out here probably once a week if the weather’s decent.”
“I’m surprised you didn’t find the body, then,” I said. Looking to my right, I eyed the crime scene tape staked out around the big pine.
“I was out here on a Monday about three weeks ago,” he said. “Then I was off for a week-not that week, but the next one. Hiker found him on a Sunday, day before I got back. So it could’ve happened anytime during those thirteen days. Pretty big window of time.”
I did the arithmetic; at the outside, the murder had occurred twenty days ago; at the inside, a mere eight-but that seemed too recent, given the decomposition of the lower legs. “Well, if we’re lucky, we can narrow it down a little more than that,” I said. I walked slowly toward the tree, bent over to study the ground closely. After stepping over the tape, I knelt and continued the last six or eight feet on all fours.
Jess had shown me the report from the evidence techs who’d worked the crime scene. They’d done a reasonably good job, it sounded like, including collecting some key insect evidence. Since the creation of the Body Farm-and partly because of research conducted there-forensic entomology had advanced remarkably. In our first pioneering study of insect activity in human corpses, one of my graduate students had spent months studying the sequence of bugs that came to feed on bodies, making detailed notes about what bugs appeared, and precisely when. While observing and collecting bugs, he also fended off food-crazed blowflies, the first and most numerous visitors, as they landed on his face and tried to crawl into his own nostrils and ears and mouth. Within seconds after a body bag was unzipped, he had documented, the blowflies began homing in on the fresh scent of death; within minutes, some of the females would begin seeking out the body’s moist orifices or bloody wounds as ideal spots to lay masses of eggs, which looked rather like dabs of grainy white toothpaste. And sometimes within only a few hours after a fly laid her eggs-especially in warm weather-they would hatch into hundreds of tiny maggots, the larval form of the blowfly.
Now, years later, most crime scene techs knew to collect the largest maggots they could find on a body, as those would probably have hatched from the earliest flies to find the body. By collecting and preserving those maggots and sending them to a forensic entomologist, the crime scene techs could get a pretty good idea how long ago the murder had occurred. The best-trained techs would also keep a few of the largest maggots alive, and make careful note of when they encased themselves in a pupa case, or puparium-the inelegant maggot’s version of a caterpillar’s cocoon-and record when the metamorphosis into the adult insect occurred. The only difference was that instead of a beautiful butterfly emerging from its cocoon, what would emerge from the puparium would be a young blowfly, which would promptly home in on the body, too, if the body were still there. So far, Jess said, none of the live maggots collected from the body had pupated yet. That meant, if the collected specimens did indeed represent the earliest fly hatch, the murder had occurred less than fourteen days ago.
Even from several feet away, I could see the dark stain at the base of the tree, marking where volatile fatty acids had leached from the body as it began to decay. Drawing closer, I thought I saw the first piece of additional evidence I was hoping to see: a faint line of stain leading from the base of the tree into the edge of the woods. The crime scene report had given me reason to hope I would see this.
“Sharp eye, wrong interpretation,” I muttered.
“How’s that?” I had forgotten the forester was with me.
“Oh, sorry,” I said, “I was talking to myself. You see this faint trail of dark fluids?”
“Yeah,” he said. “A drag mark. One of the crime scene guys pointed it out to me. Said it showed the killing occurred over there at the edge of the woods-said that was the primary death scene, and the tree here was really the secondary death scene.”
“I don’t think so,” I said. “You see how the stain is darkest here at the tree, then fades as it leads over there?”
He studied the faint trail. “Maybe, now that you mention it. So what?”
“What I think we’re looking at here is a maggot trail.”
“A maggot trail?”
“Sometimes, when the maggots get ready to cocoon and turn into flies, they crawl away from the body to find a more protected place. Probably so they won’t get gobbled up by birds. And for reasons we don’t understand, when they do that, they all tend to head in the same damn direction, like a herd of sheep or cows, or a bunch of lemmings.”
“Huh,” was all he said.
“The reason the trail gets fainter as it leads away from the body is that they’re coated with goo from the body at first.”
“Goo?”
“Goo. That’s a technical term we Ph.D.’s like to throw around to impress folks,” I said. “More or less interchangeable with ‘gack.’ Also with ‘volatile fatty acids.’ Anyhow, they’re all greasy with goo when they first crawl off to cocoon, but as they wiggle along the ground, the goo gets wiped off, leaving that trail we see. But by the time they get where they’re going, sometimes they’re scrubbed off enough that they’ve stopped leaving a trail. I bet if we head in that direction, though, we can find where they ended up.”
The trail of dark stain led to the west, in a remarkably straight line about a foot wide, so I followed it into the edge of the woods. Within a few feet it began to fade dramatically, so I dropped to all fours again and crawled along through the brush. Cliff followed me upright. Just when I reached a thicket of mountain laurel that seemed impenetrable, I began to see them, mostly tucked under a protective layer of last fall’s leaves. I beckoned Cliff closer and pointed. “You see those little torpedo-shaped things, about a quarter inch long?”
He frowned, squatted down, and then said, “Oh yeah, dark brown? With little rings around ’em? What are they?”
I picked up one with my right thumb and forefinger, taking care not to crush it, and cradled it in the palm of my left hand. One end had a small round opening, revealing the cylinder’s hollow interior. “It’s a puparium-a pupa case. This one’s empty, which means the fly has already chewed his way out. So that means the body was out here at least two weeks ago.”
“So you’re saying these things tell you that the murder occurred maybe just a few days after I was out here?”
“Looks that way to me,” I said. Taking a small vial from my shirt pocket, I flipped off the cap with my thumb and tipped in the puparium from my cupped palm. Then I plucked several more from the ground, snapped the lid closed, and buttoned the vial into my shirt. “We’ve re-created the death scene at my research facility up at UT-Knoxville, using a donated cadaver. It’s been tied to a tree for nearly a week now, and it’s starting to reach the same stage of decay as the body here was in when it was found. So that argues for the same timetable.”