He waved a hand in the direction of the caged carcass. “See, we have eight of these sites, each with a rat cadaver. The rats are already dead when we get them.”
“Psychology department,” Filbert said. “Psychology generates a lot of dead rats.”
“We put them out at the same time in different conditions and then see who comes to visit at what time and for how long. We have a lot of fun, don’t we, Dr. Filbert?”
“Some of us do. The rest of us have things we’d rather be doing.”
“Dr. Filbert is feeling holier-than-thou these days because he got another grant for his macabre experiments with DNA. Justice Department, NSERC—they all love him. And why not? I created him.”
Filbert pointed to a cage further uphill.
“You see, this one has a southern exposure. That means it gets a lot of sunlight and the process of decay is speeded up.”
“Speeded up,” Arsenault said. “Looks like it’s just about over.”
“Dry decay stage,” Chin said. “All the liquids have seeped away. Picnic for the hide beetle, though.” He squatted beside the cadaver. “Yes, there they are, munching away. Yum yum.” He stood up again. “Let’s visit his cousin, shall we? Other side of the hill.”
“Doc, we need to know your findings on the previous samples we brought you. And we have something new, too.”
“Fine, fine. More the merrier.”
Chin led them down the other side of the hill toward the campus. Through the trees, Cardinal could see a lacrosse game in progress. Shouts of students echoed among the hills. A blackfly landed on his wrist and he shook it off. It landed on his other wrist and bit him.
“Now look at this. This little rodent was planted the same time as his cousin over the hill. Different side of the tracks, so to speak.”
The rat was black, and the flesh looked almost liquid.
“What do we call this stage, Dr. Filbert?”
“Black putrefaction. It’s been known to set in during some of your lectures.”
“Tsk, tsk. Such bile in one so young. Yes, it is black putrefaction. A completely different stage of decay and yet exactly the same post-mortem interval. Even more important: You could examine this rat all day and you will not see a single hide beetle.”
“Not even a married one.”
“Oh, Dr. Filbert, you are très piquant”
Once again, Chin squatted beside the cage. “Yes, you see, here we have Calliphoridae and Sarcophagidae still in the pupal stage. Amazing what a difference a few degrees can make. Winter, though. That’s a whole different story.”
“Before the snow, after the snow,” Filbert said. “Above freezing, below freezing. You’re entering whole new realms of confusion.”
Cardinal had had a few winter cadavers of his own, but he didn’t want to get into it with them. Please, can we just get to the lab? Please can we focus on the case?
Chin led them past two more cages, two more dead rats, giving them commentary as if he were a museum curator—which, in a way, he was. Finally, they were in the lab and Chin pulled a binder from a shelf. He flipped through to the end and examined some computer printouts.
“Here we are. You’re looking at a minimum postmortem interval of 312 hours and a maximum of 336.”
“Fourteen days,” Cardinal said. “But you gave us that much last time.”
“Well, now you can actually take it to the courtroom. We know beyond a doubt what the species are because we’ve allowed them to hatch. I’m sure Dr. Filbert would be happy to appear in court for you. He certainly has nothing else to do.”
“Oh, no. Just my long, lonely hours at the thermal cycler,” Filbert said. “Why don’t you show them the data?”
Chin tilted a computer toward them, and a grid lit up the screen. “Succession data. We keep developmental timetables for all the local arthropods in our database.”
“What he means is, I do,” Filbert said. “He just takes credit for it.”
“Dr. Filbert is not a scientist at all, Detectives. He is actually an escapee from a locked facility. I’d be grateful if you’d take him with you when you go.” Chin typed something on the keyboard, and the grid changed colour. Then a list appeared on the left-hand side and the grid filled up with numbers.
“On the left, we enter the taxa found at the site. Calliphoridae, Cynomyopsis, Staphylinidae, et cetera. Each has a different time of oviposition or pupaposition and a different time of development. You feed the computer all the taxa you find at the site, enter their different stages of development and, really, you don’t even need a computer. You just look at what number of days accounts for all the different stages. The only PMI that could account for all of these being in the same place at the same time is …” Chin hit Enter and the screen flashed a number range.
“Three hundred and twelve hours to 336 hours,” Cardinal said. “Very impressive.”
“Science at its most basic.” Chin looked up at them with a smile. Fluorescent lights formed bright ingots in his glasses. “Even Filbert understands it.”
“Not my field, really,” Filbert said. “I’m just a capillary sequencer.”
Arsenault pulled out a couple of vials and handed them to Dr. Chin.
“Another body,” he said. “Can you tell us anything from these?”
“Well, you’ve got mostly eggs here. Hardly any pupae. Fresh corpse, right?”
“Right.”
Dr. Chin tapped out one of the eggs and put it under the microscope. “Phormia regina you get everywhere. Boring.” He put another egg on another slide. “Lucilia illustris,” he said, adjusting the focus. “Greenbottle. Likes open, dry areas.”
“That would certainly fit,” Cardinal said.
Dr. Chin tapped out another egg onto a slide and put it under the scope. He adjusted the focus back and forth. “Phaenicia sericata. Also known as the sheep blowfly. This one lives in bright habitats. Early arriver, too. Likes to be first in line. Outdoors, in sunshine, I’d say we’re looking at the neighbourhood of twelve to fourteen hours post-mortem.”
“That would match the appearance of the corpse,” Arsenault said.
“You didn’t mention either of those species with our first victim,” Cardinal said.
“Heck, no. First victim was behind a waterfall and two weeks old. You’re not going to see either of these insects at that site. And vice versa: You’re not going to see Cynomyopsis cadaverina on a corpse that fresh. But I don’t understand why you’re coming to me about this second victim. You’ll get a reasonable time of death from stomach contents and body temperature.”
“We found something else at the second site,” Cardinal said. “Arsenault did.”
Arsenault produced another vial. Chin held it up to the light.
“A single pupal casing?”
“It wasn’t part of any masses. It was by itself eight feet away.”
“Eight feet?” Chin opened the vial and slid the tiny casing onto a slide. “Sometimes maggots can jump quite far from the flesh,” Chin said, “but this is not a cheese skipper. And your second corpse was nowhere near water, correct?”
“That’s right. No lake or stream within at least a mile.”
“This is a casing from a third-instar Cynomyopsis. There were lots of them on your first corpse. But you’ve got nothing older than first instar on the second one, and it’s not old enough to attract myopsis. No way this casing is from your second corpse.”
“Yes!” Arsenault jerked his elbow downward in the sports fan’s sign of victory.
“Hold on,” Cardinal said. “If I understand you correctly, this casing couldn’t be from the second victim, right?”