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   from the issue of December 9, 2004

     
 
Entomologists help find clues at crime scenes

 BY SUZANNA ADAM, IANR NEWS SERVICE

Sometimes, the best witnesses are no bigger than a grain of rice.

 
Entomologist Fred Baxendale, left, and Tim Huntington, an entomology graduate student, attach temperature-reading equipment to a body bag that contains...
 Entomologist Fred Baxendale, left, and Tim Huntington, an entomology graduate student, attach temperature-reading equipment to a body bag that contains a decomposing 25-pound pig. Research by UNL entomologists is helping make entomologic assumptions regarding crime more accurate. IANR photo by Brett Hampton.

For three years, UNL entomologists have examined murder scenes in the Lincoln area for creepy crawly clues - clues that help estimate a time of death and make or break a suspect's alibi.

"Forensic entomology is anytime insects and the law interact," said entomologist Fred Baxendale. "In some ways, it's a very serious business because, based on the testimony of a forensic entomologist, someone could be sent to the electric chair for capital murder."

Forensic entomology has been around for centuries but began being used widely as evidence 10 years ago, he said. If a body has been dead for more than a day, forensic entomology is one of the few sources of evidence police can rely on to predict time of death.

The Institute of Agriculture and Natural Resources forensic entomology team consists of Baxendale, colleague Leon Higley, and Tim Huntington and Paul Nabity, entomology graduate students. Huntington came to UNL from Indianapolis; Nabity is from Omaha.

They became involved with forensic entomology when Higley received a call from a universally recognized forensic entomologist with a question about the accuracy of entomological evidence. It was then, Higley said, that he began to realize the inadequacies of forensic entomology research.

"We started looking at the data in detail and realized the scientific basis for what was being done really wasn't there," Higley said. "When we discovered how poor the data were that were being used in forensic entomology cases, we felt an obligation as experts to help change that.

In the lab, UNL Entomologist Fred Baxendale and Tim Huntington, an entomology graduate student, place raw liver in a colony...
 
In the lab, UNL Entomologist Fred Baxendale and Tim Huntington, an entomology graduate student, place raw liver in a colony of blue bottle flies for them to use for egg-laying. These flies are used as part of UNL research to determine the effects of temperature on the development of forensically important blow flies. IANR photo by Brett Hampton.

 

"This is one of the rare instances where as a scientist I get the opportunity to do work that has an immediate benefit."

The team subsequently began a partnership with the Lincoln Police Department. So far, the entomologists' expertise has been required in five local murder cases, the most recent in May. In at least two of those cases, their testimonies have been key in solving the case.

"We drop what we're doing and go when we're called," Baxendale said. "There's an urgency to collect evidence because insect evidence is often destroyed quickly when investigators are gathering clues and moving the body."

Two or all of the team members go to the crime scene, where they spend six to eight hours taking pictures, collecting insect samples, writing notes and crawling around on their hands and knees searching for insects in the area around the body. The most important clues they collect are related to the time the crime occurred, Higley said.

Working around dead bodies wasn't as disturbing as he thought it might be.

"I found that I had no emotional reaction," Higley said. "Apparently, I just see the body as tissue, the person is long gone."

The work is very precise, requiring numerous samples and temperature readings, perhaps over three or four days, Baxendale said.

Insects are on the scene quickly after someone dies.

"Five minutes after death, flies will find a body on a warm summer day," Baxendale said. "In 30 minutes, the insects are laying eggs. We take this information and work backward."

Because insects are cold-blooded, their growth and reproduction varies directly with the temperature of the surrounding area. By correlating temperatures with the weather station closest to the crime scene and observing the stage of insect development, forensic entomologists can fairly precisely estimate the time of death, he said.

Their painstaking precision is critical because a difference of 3 degrees in temperature could cause the prediction to vary by three or four days, Baxendale said.

As the entomologists got more involved in crime scenes, they noticed more insufficiencies in pre-existing forensically important data.

Different insect species develop at different rates, which are affected directly by slight differences in temperature. A forensic entomologist's method of estimating temperatures could alter the result. Often, the most certain estimate an entomologist can give is within a time frame of 18 hours, Higley said.

Based on those and other concerns, Baxendale and Higley helped Huntington and Nabity launch research to increase the accuracy of entomologic assumptions regarding crime.

The students are investigating the lowest temperatures at which insects will begin the development process and measuring development rates for different species at varying temperatures. They also are examining accurate measurement methods and whether other factors could alter development processes, Higley said.

Only a few other institutions internationally are involved in this type of research.

The team's increasing knowledge of forensic entomology also has been useful in the classroom, and not just because it provides anecdotes to grab students' attention in entomology classes.

"Based on the first murder case we worked on, we recognized a growing need to train crime scene technicians to recognize and collect evidence," Baxendale said.

In 2001, the team conducted its first training sessions for the Lincoln Police Department and later trained FBI officers at the Omaha regional office. The team recently finished its third workshop with a Nebraska Wesleyan University forensic science class. Combined, the forensic entomologists have trained more than 100 Nebraska police officers and 150 students.

"There are a vast number of different cases where you could use forensic entomology information," said Sgt. Erin Sims, a Lincoln Police Department officer who attended one of the training sessions. "But it all looks like dirt until you get used to looking for insects. Most people aren't used to looking for details like that."

Because the partnership between police and the university has proven beneficial for both parties, the forensic entomologists are hoping to expand their training programs to reach police across the state.

"We have as much or more cooperation than any other forensic team in the country," Higley said. "There's no question there's a very strong need for this sort of work."

The university has continued to expand its forensic entomology class and workshop offerings. In spring, Higley will lead the entomology department's first forensic entomology course for entomology and criminal justice majors and police officers.

This research is conducted in cooperation with IANR's Agricultural Research Division.


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