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The testimony of bugs

Work of forensic entomologist is solving crimes

Most of us pay no attention to the insects around us.

The stinging and biting variety can annoy us and the multi-limbed ones can give us the creeps, but for the most part they have little impact on our lives.

But ignore them at your peril, especially if you have broken the law.

These days insects are testifying in all sorts of crime cases thanks to the groundbreaking work of forensic entomologists, such as B.C.'s own Dr. Gail Anderson.

A recognized leader in the field Anderson, of the Simon Fraser department of criminology, has used her decade of research to help the authorities in over 120 cases.

The science is not new. In AD 1235 Chinese investigator Sung Tz'u solved a slashing murder by ordering village residents to bring forth their sickles. A swarm of blowflies descended on one suggesting the presence of blood and after being confronted the sickle's owner confessed.

But new technology has made the science a must for many high profile cases of violent crime.

In a recent American case crime scene experts extracted human DNA from blood-engorged pubic crab louse found on a woman who had been raped and left for dead.

Detectives matched the sample with DNA from a suspect who was infested with lice.

This is ground-breaking science for the future as it could be used in cases where a person is presumed murdered but their body is missing.

If insects were attracted to the dead body and fed and laid their eggs then the body was moved it is possible DNA from the victim could be retrieved from the guts of maggots left at the scene of the crime.

In another infamous case the body of a murdered woman was found with the mangled remains of a grasshopper in her clothing.

During a police search of the suspect's pant leg cuff the left hind leg of a grasshopper was discovered. The pest parts matched perfectly.

But in most cases forensic entomologists like Anderson use bugs to help determine the time of death.

Often called to testify in court cases, she can help make the job of the jury a bit easier by using science as a guide.

"I can't tell the jury who is telling the truth," said Anderson who was nominated by Time magazine in 1999 as one of the top innovators in the field of crime and punishment. "But I can tell the jury who is lying because I will give a date and that date is going to only fit one scenario, so it will eliminate somebody.

"In those kind of cases the entomological evidence may be absolutely crucial."

Anderson has research projects in almost every province.

The variety of projects is a must, she said, because bugs vary from location to location and behave differently under diverse climatic conditions.

She is also studying how bodies decay in the water, how drugs ingested by bugs affect life-cycles, what bugs can tell us about elder and child abuse and how bugs can help catch poachers.

"From a poaching point of view it could simply be to determine whether the animal was killed in or out of season, whether it was a crime or whether it was not," said Anderson.

"We can also tell if the carcass has been moved from one place to another, whether dismemberment has occurred, where the wound sites might be, and things like that.

"Different species of insects will colonize in different areas so the wrong insects on it for that area might be able to tell where it came from."

Altitude, for example, will mean the bugs in Whistler are different from the ones in Vancouver.

In a US case a man claimed he had legally killed a bear. But, when the hide was examined by an entomologist he found a tick which only lived in New York State. The man's bear-kill licence was for another state altogether.

Anderson said time of death information could also be used to catch sheep hunters who go in by helicopter.

For example, a sheep hunter may shoot first and ask questions later, said Anderson. When the hunter goes to get the carcass it is discovered it is too small to hunt legally,

"So the hunters sneak away quietly," said Anderson.

"Now we can pin point the time of death of that animal and we can tell exactly who was in the area because they are records of the helicopter flights."

Anderson is also investigating decomposition in the water. In the past she had placed pig carcasses in the waters of Howe Sound to study what happens.

She found many differences in how sea life interacts with decomposing dead bodies compared to how terrestrial insects use decomposing matter.

The science involved in this field is quite straightforward. Insect species are attracted to decomposing remains and their offspring develop according to specific timetables. By examining these bugs scientists can pinpoint the time of death.

Only a few types of insects eat rotting human flesh. The two main players are the carrion feeders or blowflies and the flesh flies. Beetles also arrive on the scene.

Flies and beetles arrive at different times depending on the decomposition of the body.

If something dies a blowfly will find it, usually within an hour. When the females get to the body they go into a frenzy of egg laying so each dead animal or body creates a whole new generation of flies.

Not long after they are laid, the eggs hatch. But different species of fly hatch at different times and that is just one reason proper identification of species is so important to the puzzle. In some cases forensic entomologists will raise pupa from the scene in their labs to ensure the correct identification of the bug.

At the crime scene the eggs hatch into maggots, form a mass and eat away at the body. The maggots turn into immobile pupa waiting to metamorphasize into adult blowflies.

By studying these life cycles and the environment in which they are found forensic entomologists can give an estimate of the time of death.

Throughout this cycle other species arrive on the scene. Many come at predictable rates helping further pin down the time of death.

Experts also look for key signs at the crime scene. For example if there is a high rate of infestation around the genitals on a victim it could be an indicator of rape or sexual assault as the blowflies are attracted to the tiny lacerations which occur with this type of crime.

If there is no infestation around the mouth it can be an indicator that the person has committed suicide by swallowing insecticide.

Anderson and other colleagues are working on a nationwide data bank of bug facts to help investigators with crime scene analysis.

She is also working to educate conservation officers so clues can be gathered and used successfully in courts to catch poachers.

But as exciting as getting the bad guys, said Anderson is exonerating the innocent.

"Maybe that is just as important if not more so," she said.