Continued from previous page The science of forensic entomology is based on the fact that a variety of insects invades and decomposes bodies in a regular, orderly pattern. "The green bottle flies, which we call blowflies, find you just as you die," Kimsey says. "They're remarkably clever at locating a dead person. Volatile hydrocarbon gases are given off a body almost immediately after death that these flies recognize. They're attracted to the odor of blood, they're attracted to the odor of wounds in general, they can detect the perfumes in the air. Often they're there before you die. If you're lying wounded, they'll be laying eggs on you when you're still alive and conscious." The detective work depends on knowing the life cycles of the flies. "The first thing you have to know is that the rate of [the flies'] development is temperature-dependent. If it's cool, it takes longer; if it's hot, it's shorter. Insects are cold-blooded,so they don't regulate their own temperature. Instead, their metabolic processes are dependent on the outside temperature. So by knowing what the ambient temperatures have been for a week or so and then by looking at the maggots' stage of development, you can actually get a pretty good estimation as to when that person died, up to eight or nine days. "There's another feature we've recently been able to characterize. There's a very stereotypical top-down decomposition of a corpse in the presence of insects. The head is the very first part of the body that's invaded, along with whatever wounds may be present. The reason is that you've got all those portals of access, like the ears, the eyes, the nose and the mouth, where the eggs are laid. The maggots that are hatched out of those eggs go into those orifices and start the decomposing process almost immediately. So the first organs that are gone are the eyes and the brain. The skull can be hollowed out in a very short period of time, within just three days or so." The picture Kimsey paints doesn't get much prettier from there--but it is so consistently patterned that it can provide much information about the time and place of death. After the skull, the trachea, the esophagus and the major arteries of the neck provide entry into the chest cavity. When that meal is finished, the insects travel down to the abdominal cavity. "Actually, very soon after death, almost all of the major arthropod groups are there. It's just that the flies whose larvae develop very rapidly do most of the early decomposition. The beetles are there very early, but it takes their eggs longer to hatch. Then after the flies and beetles, there are a large number of mites. Much later on there are other flies, like the one we call the cheese skipper, that come very, very late in decomposition, when the animal or human is almost entirely dried out. They have larvae that hop and jump, just like a flea. There are also beetles that arrive, not to decompose the corpse, but to feed on the maggots that decompose the corpse." Asked about the worms that are famously mentioned in imaginative literature ("Let's talk of graves, of worms and epitaphs," bemoans Shakespeare's Richard II as he contemplates the end of his regime and his life), Kimsey says that image is purely human folklore. "I have yet to find earthworms or any other kind of worm infestinga corpse. The worms that I think are being referred to are the maggots of flies." Kimsey notes that insect knowledge can explain the circumstances as well as the timing of a death. "You might find a corpse in an open field, its clothes heavily infested with cockroaches. Well, domestic cockroaches are simply never found in random ecosystems. They're associated only with human beings and then generally only where the domicile is very heavily infested. Chances are that corpse became a corpse in an infested domicile and was later dumped in an open field." Sometimes finding the usual insects on a body means something unusual has occurred. "There are certain species of flies that refuse to lay their eggs in the shade or in dark conditions," Kimsey says. "So when you find the maggots of those flies infesting a corpse that's inside a barn or inside the trunk of a car or in the shade of a tree, you've got really good evidence suggesting that the corpse was moved from some other place." Sometimes the absence of insect evidence provides a clue. A year ago a Northern California woman was arrested in the death of her 670-pound daughter. The mother was charged with felony child neglect and abuse, with part of the evidence being a series of small lesions on the back of the child's feet, suggesting cockroaches or small rodents might have been feeding on her feet. In this situation, Kimsey could validate that it was almost impossible for those lesions to have been caused by an insect or rodent of any kind. Kimsey's students are taught this science not only through the examination of dead pigs but are also given an opportunity to experience a human autopsy. A field trip to the Sacramento County coroner's office has been part of the course for those students who Kimsey believes are stable and mature enough to handle the experience and benefit from it. The first group of five students to go encountered what Kimsey calls "the worst kind of decomposition case you can imagine. The stench was unbelievable; the remains had decomposed to the point that the head had come off the body. When I took the kids into the decomp room there, they were in a state of shock for 10 minutes or so. "But all I had to do was say, 'OK, we've got a situation all of you know how to handle. You've had the classes, and you've heard me talk about this. Now divide yourself up into a couple of teams, one taking the clothes and the other taking the body, and sample in the way you know how.'" Kimsey pauses. "And you know what? They did it. I was never so proud of any group of people in my life. Even the coroner's office people had a horrible time with this one. There were some serious reactions to it. But I was extremely proud of the way the students handled it. They did just a magnificent job." Kimsey says the ride back with the students in his minibus was very quiet. He checked back with them all a few days later and "they were all okay. It had been a very deeply moving experience for them. There's no question about that. But they handled it, and they are better people for it. It's not an easy thing to do, to go over a dead human being and collect the maggots off it. You could tell that they had aged a little bit that day." Kimsey attributes the extraordinary student interest in the course to factors other than the underlying macabre subject matter. "First, there's simply a greater demand for people qualified to testify in court regarding entomology," he says, citing the large and growing number of civil cases requiring insect expertise. In his own work as an expert consultant over the past decade, some 80 percent of the cases in which he has been called upon to provide an opinion are civil matters. "Then there's the simple fact that this area has become quite topical in the media," Kimsey says with mixed emotions. "Now there are whole programs devoted to entomology, with shows like The X-Files having entomology woven into the story lines." He credits the 1992 Oscar-winning film The Silence of the Lambs for "putting bugs right at the top of the public's mind." Kimsey also notes the popularity of detective novels with forensic specialists, like those of best-selling author Patricia Cornwell. "The novels are bloody awful, with an unbelievable forensic pathologist," he opines, but they're helping to popularize the field. Roger Sher, a graduate student in entomology who took Kimsey's class in spring quarter 1998, says the graduate students themselves initiated the offering of the course. "During one of our graduate student meetings, we thought of the idea and decided to ask Bob to teach it." Sher found one of the great benefits of the course to be the way it reinforces a sense of community among the students, particularly during the human autopsies, which the students do as a group. "Also, the subject matter itself, dealing with human mortality, [inclines] the living to develop really close bonds with each other." For graduate student Tonya Severson, who also took the spring 1998 class, the coursework was closely related to the general area of her doctoral study on insect development. "I was always fascinated by the idea of forensic investigations' focus on the stages of insect development," she says. More specifically, Severson became intrigued with the effect on insect development of various chemicals--like heroin or cocaine in a body, or pesticides in a field where a body is found. The autopsy she attended included both circumstances, since the body was that of a drug addict who overdosed in an urban park and lay in the field for some days before being discovered. While the partially decomposed corpse and its attendant odor were somewhat disturbing to Severson, even more unsettling were the social circumstances surrounding the death. What she found particularly troubling was that people had been aware of the body in the park for days, but no one had reported it. "What did it mean that no one would step up and do that?" she asks. "And this was a park where children were playing." Sher, too, found the autopsy experience a bit troubling--it gave him a couple of sleepless nights--but, he says, it really only confirmed what he had "already envisioned." Severson says that it deepened her understanding of how temporary life really is. "It made me decide that I just want to make sure that I'm doing what I want to do in my life and to be sure to have fun doing it."