From the issue dated May 13, 1992
Forensic Entomologist Tells Gruesome Tales of Foul Play
By Peter Monaghan
Pullman, Washington -- About a dozen times a year, E. Paul Catts receives a shipment of insects with a gruesome tale to tell.
In specimen bottles sent to his laboratory at Washington State University, Mr. Catts finds larvae and adult specimens of various insects, suspended in growth at the moment a crime-scene investigator took them from a dead human body and dropped them into preserving fluid.
It is the nature of Mr. Catts's work that most of the bodies are of victims of foul play.
Mr. Catts, a professor of entomology, uses the evidence, which comes from around the Northwest and sometimes further afield, to estimate the time of death of the body that was host to the insects. That information, crosschecked against missing-persons files, can help identify victims.
More dramatically, it can narrow down, often to one, the number of murder suspects. The time of death may, for example, point to a person who was in the victim's company. Or the types of insects found on a body may help investigators scuttle an alibi by showing that a murder did or did not occur at the discovery site, or at another location.
Mr. Catts is one of a small band of forensic entomologists around the country who use their knowledge of insects to assist law-enforcement officers and other investigators.
Wayne D. Lord, a special agent who trains colleagues in the collection of forensic-entomology evidence at the Federal Bureau of Investigation Academy in Quantico, Va., says: "Forensic entomology is becoming more and more prominent as a part of criminalistics," at a time when techniques from a wide variety of scientific disciplines are emerging in "an explosion of technologies."
Mr. Lord, Mr. Catts, and several colleagues recently published Entomology and Death, a manual of forensic-entomology findings and procedures used by investigators and other specialists.
Typically, medical examiners are able to fix the time of very recent deaths. Forensic anthropologists work at the other extreme of human decomposition -- with the skeletons that remain after insects and other animals have done their work. Forensic entomologists work with the long period between those extremes.
The first recorded use of insects in this way dates from 13th-century China, but the discipline's modern era began with cases and studies in France in the mid-19th century. Not until the 1970's, however, was it practiced regularly, aided by such researchers as Bernard Greenberg, recently retired from the University of Illinois at Chicago, who compiled many forms of baseline data about such aspects as the development of the blowfly pupal cases, or puparia.
As recently as 10 years ago, the number of forensic entomologists in the United States was small enough that most could gather around a single table at entomology conventions. They dubbed themselves "the Dirty Dozen."
Their number has grown to about 20, but forensic entomologists suspect their line of work will never attract many colleagues. Even the more mundane aspects of the discipline, such as testifying in lawsuits involving insect infestation of food products, require dealing with unsavory evidence. "We are not at a place where even a large city can support one forensic entomologist," Mr. Catts said.
In his laboratory here, Mr. Catts is studying samples, sent to him by Montana authorities, of insects found on the bodies of a husband and wife who were shot dead. In investigating such cases, forensic entomologists gauge the age of insects on corpses, based on such features as the length and mass of larvae. They need to be versed in the life cycles and types of insects in a given region, and in the comings and goings -- researchers call it the "succession" -- of many kinds of insects and larger scavengers.
The succession of insects to a corpse, researchers have found, occurs in a predictable pattern of overlapping waves over a period of years. Blowflies and other flesh flies arrive within an hour. Next come smaller flies; then beetles and wasps that feed on the fly larvae -- or maggots -- and then on dry remains. Often, dogs scatter body parts, disrupting the succession.
The process of fixing the post-mortem interval is simple to describe but no easy task to perform. In addition to weather, other variables may cloud the picture: Was the body clothed? Or bundled in a blanket or plastic, or buried, burned, or under water?
Painstaking investigations of such variables are being conducted around the country.
At Louisiana State University, C. Lamar Meek, professor of entomology, is investigating the way the blowfly invasion of corpses is affected by such surrounding environments as pastures, ponds, pine forests, and mixed hardwood forests. In another set of tests, into delayed invasion, he placed dead pigs in the trunks and passenger compartments of cars and left them to decompose.
Pigs are widely used by forensic entomologists to model human decomposition.
At the University of Hawaii at Manoa, M. Lee Goff, associate professor of entomology, has been studying how the presence of traces of illicit drugs in the tissues of corpses affects the rate of larval development. The work has had the unanticipated benefit of showing that, long after decomposition has made fresh tissue samples unavailable, the puparia of insects that have fed on the corpse can indicate whether drugs were present in the victim.
At the University of Tennessee's Anthropological Research Facility, unclaimed bodies from medical examiners' offices are laid out, within a fenced enclosure, to decompose. The facility's main purpose is to build a library of skeletal remains for forensic anthropologists, but some entomological research has been performed there.
In 1989, Neal H. Haskell, a veteran crime investigator who is completing a Ph.D. dissertation at Purdue University on blowflies, visited the facility for what he calls "an extremely enlightening experience." In an experiment intended to compare the decomposition of pigs with that of humans, he took several samples from a decaying human body each day for 35 days, and studied the insect succession at close range.
Mr. Catts's involvement in forensic work began in the 1970's. He, like others in the field, does not work full time on it. His major research, here and earlier at the University of Delaware, has been into livestock losses caused by insect infestation. He teaches courses in medical entomology to students of entomology, veterinary science, and wildlife biology. He also offers a course for non-science majors on the place of insects in world history.
His work has aided in the prosecution of several murderers. Some of his cases have been part of a continuing, intensive investigation of the "Green River" serial killings near Seattle. He is proudest, however, of his analysis, with Mr. Haskell of Purdue University, of a 1989 case involving the discovery in the Cumberland Mountains of Tennessee of the skull of a 15-year-old girl. It had a nest of paper wasps inside it. Mr. Catts and Mr. Haskell knew that the skull had had time to dry out after the completion of blowfly activity. Taking meteorological and other conditions into consideration, they were able to determine that she had been dead for 18 months. That information led to the girl's identification.
Mr. Catts works on cases in his laboratory; he is still waiting for his first opportunity to visit the actual scene of a body's discovery. By contrast, Mr. Goff in Hawaii never has far to travel to discovery scenes on the small island of Manoa. He has built so close a working relationship with the police, he says, that "they'll sometimes wait for me before they do anything." That is ideal, he says, because "no matter how much I train them, an entomologist will generally find things they won't."
Because the work of forensic entomologists is ghastly, Mr. Catts says, they, like other crime investigators, build a measure of self-protective humor into it.
"You have to have a sense of humor to do this work," he says. But he sounds only half-convinced that even that helps.
"Sometimes I see some of the photos that come in and I'm really sickened by it, that someone would waste a human life like that, and to do it in that way -- not just to murder them but to brutalize them or batter them."
Copyright © 1992 by The Chronicle of Higher Education
