Volume 6, Number 3, 1997

Insect detectives preeminent in "new" investigative field

The use of insects to solve crimes, an investigative technique pioneered by the Chinese in the 13th century, has arrived on the scene in the United States, with assistance from several University of Delaware alumni.

Forensic entomology was first used in the U.S. in the early 20th century, but it has only gained acceptance over the last 20 years or so due, in large part, to the work of the late Paul Catts, AG '52, '57M, a former UD professor.

Delaware alumni-Wayne Lord, AG '79M, and John L. "Jack" Webb, AG '92, '96M, are two of only three law enforcement officers nationwide who specialize in this field. Lord is a special agent in the FBI's child abduction and serial killer unit, and Webb is a Delaware State Police trooper.

Most forensic entomologists teach and conduct research in academia, as Prof. Catts did, and they assist police investigations on the side.

Forensic entomologists use insect evidence to arrive at a time of death, to determine if a body has been moved and, in some cases, to find the cause of death. Entomology also has been used in court to bolster charges of rape and child neglect. Webb cites a Maryland case he consulted on while a graduate student at the University. The medical examiner called him with a simple question: "Do cockroaches feed outdoors in freezing temperatures?" They don't, Webb said, because they wouldn't be able to digest. Investigators were thus able to determine that the person whose body was found behind a city residence had been murdered indoors, left there for some period of time and then dumped outdoors. Webb's testimony on the insect's dietary habits helped link the victim to a suspect whose home was infested with roaches.

As is often the case, the entomological evidence here was just a piece of the puzzle. "It might be the key piece of evidence in one out of a thousand cases," Webb says. "Forensic entomology is not the silver bullet, but the more ways you have of looking at a case, the better."

Entomology most commonly aids investigators in cases where a corpse is found days or years after death, often in fields or wooded areas. Prior to 72 hours, a test of the vitreous humor, the clear jelly that fills the eyeball behind the lens, can be used to estimate time of death. Many days later, forensic entomology may be more useful.

"Cases where the remains of humans are badly decomposed are notoriously difficult to work with," Lord says. "There are lots of limitations to traditional investigative methods."

With no witnesses and no identification on a body, investigators have few clues to solving the murder. But, entomological evidence can help investigators arrive at a time of death when other, more traditional methods fail. Armed with such information, investigators can search missing persons records to help identify the victim.

Because different species of insects invade a corpse in waves, Webb explains, the type of insects present can help pinpoint how long a body has been exposed. The first wave includes blow flies, which lay eggs that turn into worm-like larvae known as maggots. Later waves of invading insects include scavenger and dung flies, beetles, mites and moths.

The type of insect found also gives clues, since different varieties of insects inhabit different environments and geographic regions. For example, if a body that's been found in a moist environment contains dermestidae (a type of beetle that infests stored grain products and is found only in dry environments), investigators know the body has been moved.

Even the location of maggots on the body can help investigators determine cause of death. In one suburban Maryland case, entomological evidence helped solve a murder years after the body of a woman had been buried. Originally, she was believed to have died of a drug overdose. Much later, a police officer who had attended a seminar on entomology noticed that the maggots in photos of the corpse were in atypical places. Maggots cluster on exposed, moist body orifices-eyes, nose, mouth. But, on this woman's body, they also were on her chest, neck and palms, indicating trauma to those areas.

After exhuming her skeletal remains, forensic anthropologists determined from knife marks on her ribs that she had been stabbed to death, the wounds on her hands resulting from efforts to defend herself. Her boyfriend was arrested and convicted-nearly five years after her death.

With so few forensic entomologists in this country, how is it that the University of Delaware has educated several of them, including two-Prof. Catts and Lord-considered preeminent in their field? Prof. Catts' 1990 illustrated book Entomology and Death: A Procedural Guide (edited with Paul Haskell of Purdue University) remains an indispensable resource for law enforcement officials. It serves as a primer on arthropod biology and provides instruction in collecting and analyzing entomological evidence.

Lord, the only forensic entomologist in the FBI, has consulted on cases across the nation and has taught seminars at the FBI Academy and elsewhere. He's the first person many police departments contact when they need entomological assistance.

Prof. Catts was one of Lord's professors in the '70s. By the time Webb arrived on the scene, Prof. Catts had accepted a teaching job at Washington State University, but his influence continued to be felt. Both Prof. Catts and Lord retained ties with the University, giving lectures on occasion. In fact, it was at a lecture given by Lord six years ago that Webb first seized upon forensic entomology as a perfect career-one that integrated his interests in law enforcement and science.

Lord has served as Webb's mentor ever since.

"For me, Paul Catts was always in the background," Lord recalls. "He was a personable man, an excellent teacher and a superior field biologist. It was because of Paul's influence that I stayed with forensics. Now, I think I've passed this lineage on to Jack Webb."

After only a few years as a police officer, Webb has already made his mark. As a graduate student, he collected and cataloged Delaware insects, an invaluable study that had never been done before. He has since received requests for guidance from entomologists all over the world who want to duplicate the study in their locales.

Webb has likewise passed his knowledge on to others. Cpl. Walter Ferris, AG '87, of the Wilmington (Del.) Police Department's forensic unit, though not formally schooled in entomology, has assisted Webb with his research. He, Webb and Newark Police Sgt. Tom Le Min, another person informally trained by Webb, have all taught courses in forensic entomology to police officers across the country.

Webb also teaches courses on forensic entomology-"toned down a bit"-to the public. "These people are prospective jurors," Webb explains. "I want them to see that there's a lot that goes into working on a homicide, rape, kidnapping or any case. And, that we take every case very seriously."

Lord says his experience at the University of Delaware taught him the two key components for success in forensics. "First, you have to be good at science," he says, "and the University of Delaware has one of the best entomology departments on the East Coast."

The second component, he says, is ethics.

"At Delaware, particularly with Catts, Roland Roth [professor of entomology and applied ecology] and other faculty, I got a real sense of the ethical base they stand on in their personal and professional lives," Lord says.

"Ultimately, ethics may be the most important factor for success in forensics."

-Theresa Gawlas, AS '94M