A forensic entomologist specializes in the developmental stages and behavior of different types of insects found on a cadaver at a crime scene. They provide indicators about the time that has passed since the person's death (PMI), although this is not an exact science. They also indicate something about the climate and locale in which the death may have occurred.
A prominent physical anthropologist who developed expertise in entomology is Dr. William K. Bass III, who runs the Anthropological Research Facility at the University of Tennessee at Knoxville. This two-and-a-half-acre field is dedicated to the study of decomposing human remains, and the presence of more than a dozen bodies at any given time exhibits their ongoing projects. The facility—dubbed the Body Farm by the press— has made important contributions to estimating the PMI in suspicious deaths.
Bass, an expert on skeletal identification, pioneered this unusual research over thirty years ago when he discovered that the field's state of the art was "mostly anecdotal." Moving to Tennessee in 1971, he got involved in cases where corpses were infested with insects. "Half of my first ten cases were maggot-covered bodies," he recalls. "I didn't know much about that, so I looked through the literature on the subject, and there wasn't much there."
He soon acquired a field and the unclaimed cadavers of several homeless men. As they lay exposed, they provided information about what happens to bodies under various conditions. Insects came in and became the subject of intensive study.
"Before our work, no one had ever established a time line," Bass points out. "There are many factors that can affect how a body decomposes, but we found that the major two are climate and insects. When a person dies, the body begins to decay immediately, and the enzymes in the digestive system begin to eat the tissue. You putrefy, and this gives off a smell." That attracts the bugs. Measuring and recording this information gave the facility its raison d'être.