The Body of Evidence

When it comes to crime, there's nowhere to hide from Canada's cutting-edge forensic investigators: No stain is left unturned.

The Ottawa Citizen
Sunday, April 13, 2003

Margaret Brady

PORT COQUITLAM, B.C. - The last rays of late afternoon sun bathe the yellow Caterpillar shovel in a garish glow as police investigators watch it scrape soil from a deepening pit. Tarps are draped over mounds of earth on this cratered, dusty plot within sight of British Columbia's lower mainland coastal mountains. A sign on the metal gate reads, "Stop. Crime Scene. All Vehicles/Persons Subject to Search."

Steam rises as excavators sift through soil on the Port Coquitlam pig farm of accused serial killer Robert Pickton: Grim findings for rotating teams of forensic investigators

CREDIT: Chuck Stoody, The Canadian Press

They are digging for remains.

This is the infamous Pickton pig farm. Adjacent to a golf course and overlooked by new residential housing, it appears more like a construction site than a crime scene. "The scale of the operation is formidable," says a scientist who visited the site. From a forensic point of view, it's Canada's "Ground Zero."

Robert William Pickton is accused of killing 15 women who disappeared from Vancouver's downtown eastside over the past 20 years. In total, more than 60 women, mostly prostitutes and drug addicts, have vanished from that area since the mid-1980s. Investigators at the pig farm are tight-lipped about what they are finding, fearful of jeopardizing the prosecution's case.

(Stop Crime Scene; All Vehicles/Persons Subject to Search; Authorized Access Only) 

The identification of remains in such cases would not be possible without recent advances in the forensic sciences, especially in DNA profiling techniques. Better ways of extracting and testing DNA mean evidence once considered useless can now offer great value.

However, DNA is only part of the equation. Canadian scientists and police investigators have come up with bold, imaginative and even wacky ideas about how to solve crimes. They have built an impressive arsenal of weapons in fields as diverse as odontology, entomology, foot morphology and genetic profiling.

But techniques developed in a lab are only as good as the evidence collected by investigators in the field. That's where Canada really stands out, according to Supt. Lee Fraser, the officer in charge of forensic identification services with the Royal Canadian Mounted Police in Ottawa.

"We are the best," he says, because of an ongoing training program "no one else has." He points to the RCMP's fingerprint comparison exams. "One mistake and you're toast. We have zero tolerance."

Entomologist Gail Anderson, of Simon Fraser University, is considered one of the top five in the world in her field.

CREDIT: Simon Fraser University

At least a dozen investigators from forensic identification units across the country are on the Pickton farm every day. The unremitting task of seeking minute human remains is so stressful that investigators are rotated every few weeks, with a core team managing the operation.

It is also stressful for the families whose relatives have not been identified. On the day I visited the site recently, an elderly man in a parked car, possibly related to a missing woman, watched the sombre activity for a while before driving off.

Identification of the victims is vital, says Fraser, an officer with extensive experience in large-scale death investigations. He led the forensic investigation team into the 1998 Swissair crash on Canada's East Coast. "If I realized one thing from Swissair, it is how really, really important closure is to the families," he says. "That's true for the Pickton farm too."

Forensic dentist David Sweet examines a skull at his UBC lab.

CREDIT: University of British Columbia

Of the 229 people on board Swissair Flight 111 which crashed off Peggy's Cove, N.S., the forensic team identified 2,499 individual body parts, primarily through genetic profiling requiring a staggering 180,000 profile comparisons. RCMP labs in Halifax, Ottawa, Vancouver and Regina as well as Toronto's Centre of Forensic Sciences, were involved. The grim work was completed in a surprisingly short 105 days. Investigation of the Port Coquitlam site is far more complex and could take several years, according to Fraser.

Services Stretched Thin

Forensic identification services are stretched thin by the volume of material that must be analysed in the Pickton case. At the same time, police services are trying to meet demands created by government security initiatives in the war against terrorism. These include replacing outdated machines with faster, more sensitive equipment. Another hurdle is the training and outfitting of more specialists to recover evidence from scenes contaminated by chemical, biological or radiological agents.

Forensics investigators are in a race against time at this Port Coquitlam pig farm where DNA evidence is thought to be seeping away.

CREDIT: Ian Lindsay, Vancouver Sun

"Chemicals are used to analyse a crime scene," says the RCMP's Della Wilkinson, who is working on a counter-terrorism project. "The problem is we don't want to use ones that counteract with contaminants. We also need to prevent a chain of contamination spreading through our labs. That could kill our employees."

Before the events of 9/11, Wilkinson, an Ottawa-based chemist, was already working on a counter-terrorism initiative funded through a grant from the U.S. Department of Defence. The project focuses on the challenges of recovering evidence from scenes contaminated by biological or chemical agents.

"We were on the leading edge of what then became the bandwagon," says Brian Yamashita, a chemist with the RCMP forensic identification services in Ottawa.

An arrow, drawn by forensics experts, marks the trajectory of a bullet that killed this Guatemalan man last year.

The first phase of the ongoing project examined how to recover fingerprints from contaminated crime scenes. Wilkinson, formerly a scientist with the National Research Council on contract with the RCMP, is a specialist in fingerprints. Her earlier research concentrated on the tricky business of identifying fingerprints on cadavers.

In July 2000, Wilkinson travelled with a team to Canada's Defence Research Establishment in Suffield, Alta. They exposed fingerprinted materials that might be found at a crime scene to chemical warfare agents and developed the prints to see which had survived.

Chemical warfare agents are chosen because they target biological systems and molecules, says Wilkinson. This presents a challenge because the chemicals used to delineate fingerprints are attracted to similar molecules and may fail to differentiate between prints and chemical warfare agents.

Immediately after the attacks on the World Trade Center in New York and the Pentagon in Washington, Wilkinson's research was expanded to include recovery of all physical evidence from contaminated sites.

"For example, what about the problem of analysing DNA on a tissue used to blow a nose found in a site contaminated by ricin?" she says. "How do you prevent the decontaminant agents from destroying other physical evidence?" Ricin is the deadly biological agent recently found in a British anti-terrorist raid in north London. Wilkinson hopes she can find a way to separate human DNA from chemical and biological agents so that forensic scientists can examine once-contaminated evidence in their labs.

Wilkinson's research is used by Canada's Chemical Biological Radiological Nuclear Response team (CBRN), which manages and cleans up our contaminated crime scenes. Designed to respond to terrorist devices, it is made up of RCMP and Canadian military members. In the two months following the Sept. 11 attacks, it responded to about 60 anthrax hoaxes.

"More and more of these chemicals I work with are in the news these days," says Wilkinson.

The impact of terrorist threats has also rocked the RCMP's forensic lab's explosives section. On Christmas Eve, 1999, a month after the section moved into new facilities in Ottawa, shoes and pants belonging to suspected terrorist Ahmed Ressam were sent to the lab to check for explosive residues. The Montreal resident, who planned an attack on the Los Angeles Airport, had been captured when he attempted to cross into Washington State from Canada earlier in the month.

"Not all the instruments were hooked up and operating," says section head Wendy Norman. "We were just swamped, but we got some really good evidence." The chemistry graduate from the University of Western Ontario testified at Ressam's trial in Los Angeles in March, 2001.

Terrorism-related cases take priority over other cases, such as car bombs or bank vault explosions, she says. "Because it's a wanna-be terrorist or suspected terrorist, it moves to the top of the pile. You wouldn't want to sit on a sample for six months and have someone like Ressam blow something up."

The section has received a much-needed infusion of money for new equipment and more staff. "I have money to spend that I haven't seen in 30 years -- a luxury we haven't had," says Norman. "Luxury's actually not the right word. It's a necessity."

The lab has to follow meticulous procedures for each sample or evidence won't stand up in court. "The work generated from a single swab can take hours of technologists' time and my time," says Norman. "There's nothing quick that we do."

Identifying the deceased so that family members and friends can begin the grieving process and try to come to terms with their loss is of great importance, says David Sweet, director of the Vancouver-based Bureau of Legal Dentistry. The lab has helped Wilkinson's counter-terrorism team study decontaminated DNA samples. "Forensic dentists know that sometimes only through our efforts can this intrinsic societal need be fulfilled."

The forensic odontology lab on the campus of the University of British Columbia is the only one in North America and one of a handful in the world. Traditionally, this science involves victim identification using dental charts and estimating factors such as age or lifestyle through growth patterns and tooth condition. More recently, the field has expanded to include bitemark analysis, which is the evaluation of dental impressions on soft surfaces, most commonly the skin. About 80 per cent of violent crimes involving physical contact, such as rape, sexual assault, sexual homicide and physical abuse, involve biting -- either offensively or defensively.

Sweet's lab, established in 1997 by a grant from the B.C. Attorney General, is the only odontology lab in the world to analyse teeth and bones using DNA testing.

The advantage of DNA is that it is present in all body cells and doesn't change after death, says Sweet, who has testified as an expert witness in courts throughout North America, the Caribbean, Europe and Africa. His focus on DNA stems from his doctoral work, completed at the University of Grenada on DNA in saliva found on bite marks.

The most resilient body tissues are teeth and bones. Teeth were once considered poor sources of DNA. The lab now uses a cryogenic freezer mill, more commonly used by geologists for mineral extraction, to maximize DNA extraction from teeth and bones. The mill uses liquid nitrogen to keep the tissue cold and brittle so it shatters when pulverized and the resulting powder is analysed. Advances in DNA research mean increasingly minute DNA samples can be profiled successfully.

As a source of DNA, teeth are more stable than bones because they are harder and more resistant to environmental damage. Sweet says, for example, that teeth are far more likely to survive fire in cases of immolation. Exposure to salt water or acidic soil can leach DNA from bones, a potential problem for the Pickton farm investigators.

The longevity of hard tissue is evidenced by the lab's work in a 50-year-old cold case known as the "Babes in the Woods." When two children's skeletons, draped by a woman's coat, were found in Vancouver's Stanley Park in 1953, a pathologist and anthropologist identified the bodies as twins. They also said one was a girl and the other a boy, an error that misled the resulting police investigation. Despite the passage of time, Sweet's lab was able to get DNA profiles that proved the children were both boys, were not twins and were not even the same age. Unfortunately, they still have not been identified.

Sweet's lab recently established the relative quantities of DNA available from different types of teeth, such as incisors, canines, premolars and molars. Molars contain the most DNA but all teeth contain enough for analysis. Research in the lab, which involves Sweet's students, also examined the amounts of DNA in different tooth parts. The tip of the crown, which might break off in a fight, is the only part that can't be profiled.

However, Sweet is concerned that the lab's original raison d'etre -- research -- is being jeopardized by lack of funding. Operating costs are paid for by the 140 or so cases the lab handles each year. "There are no funding agencies in Canada for forensic research so we are turning our attention more and more to casework," the UBC professor says. "I don't spend time at the lab bench working on ideas. I spend my time on the sidewalk talking to people trying to raise funds."

Research funding is also a concern for forensic entomologist Gail Anderson, named one of the five leading international innovators in the field of crime and punishment by Time magazine in 2001. An associate professor in Simon Fraser University's school of criminology, in Burnaby, B.C., Anderson heads the only North American laboratory dedicated to researching the ways insects can be of help in crime scene investigations.

Forensic entomology, the study of insects associated with dead bodies, has a history that goes back at least as far as 13th-century China. Primarily, it's used to determine the time of death.

In cases of death on land, blowflies are generally the first insects to colonize a body, beginning to lay eggs in wound sites and bodily orifices within minutes of death. An evaluation of the oldest bugs provides a minimum post-mortem interval. Time of death can also be determined by examining the order in which insects are attracted to a corpse. They arrive because they wish to feed on rotting flesh or on other insects already there. The sequence is entirely predictable, says Anderson, who examines entomological evidence for up to 20 cases a year. About one-quarter of these are homicides.

Anderson's goal is to create a nationwide forensic entomological database of insect "witnesses" and their life-cycles. Much of the work has been completed for land-based bugs, especially for Western Canada. In recent years, she has begun to compile information on marine and freshwater creatures. She has applied to the National Sciences & Engineering Research Council for funding to expand this research.

Pig corpses are used by Anderson for her research because of their similarity to human beings in torso size and skin type. Sometimes pigs are dressed, or partially dressed, to simulate how insects or marine fauna react to clothing. Her research records factors such as climate, humidity, temperature, sun, shade and geographical regions.

Anderson and her students are also beginning to research cases of animal abuse or neglect. Some veterinarians they contacted reported up to 30 suspected cases a year. Their work will focus on maggots as wound indicators. "The Society for the Prevention of Cruelty to Animals is very interested in working with us on this," says Anderson. "It's very impressive evidence."

Other crime scene evidence can include blood spattering. Blood is an excellent source of DNA and it is also useful in crime reconstruction. By tracing the trajectory of blood drops, investigators may determine such factors as the force of attacks, the number of blows or shots and the location of victims or perpetrators. Cast-off stains will show how a weapon was swung and other patterns might show a victim was dragged along a floor. It may be used to refute or corroborate witnesses' testimony.

It was a Carleton University nuclear physicist who developed the world's first computer program for analysing these gory stains. Fred Carter, founder and president of Forensic Computing of Ottawa Inc., says he fears little competition because the market for such software is so limited. Still, he has sold his BackTrack/Win and Backtrack Images program to police forces in Europe, Asia and Australia as well as throughout the U.S.

In the 1980s, the RCMP had approached Carter to teach the fundamentals of physics to blood spatter investigators. At the time, bloodstain analysis involved tying strings to blood and extending those strings to a point of apparent convergence. Although the crude system sometimes worked, Carter quickly realized that it was cumbersome and time-consuming. He came up with a solution based on virtual strings to recreate the flight path of the blood droplets.

The evidence is gathered by digital cameras and is analysed by computer. Conclusions do not depend on unknowns such as the size or speed of the droplets, says Carter. From a bird's-eye view, as seen on the computer, the strings are seen to converge, indicating the probable source of the blood. The side view shows the upper limit for the height of the blood source. Canada leads the world in this discipline.

Another area of Canadian expertise is foot morphology. This is the analysis of marks left by feet either at a crime scene or in footwear linked to the scene. Sgt. Robert Kennedy of the RCMP forensic identification section has built a database of 12,000 pairs of feet in an effort to prove the uniqueness of human feet and has evaluated foot impression evidence from crime scenes in many countries. Recently, he successfully defended a court challenge to the scientific reliability of testimony in a second-degree murder case. The judge's ruling, which recognized Sgt. Kennedy as an expert who did not overstate his evidence, set a precedent in barefoot-impression evidence.

Pressure areas on the soles of the feet can be shown to match sweat impressions left in a bloodstained boot. Impressions are photographed and sometimes enhanced with chemicals or forensic lighting or lifting techniques. Inked impressions, both standing and walking, are taken of the suspect's feet.

The identification of barefoot impressions can also be used at times of mass disasters where only a foot might be found. It may also differentiate between identical twins, something that can not be achieved through DNA profiling.

Forensic scientists learn from new cases. A large, complex investigation such as the painstaking one on the Pickton farm presents new problems that will likely evoke new answers.

"Sometimes the very elegant lab solution is far too complex and delicate to ever cut it in the streets," says Wilkinson, who holds a doctorate in chemistry from Cambridge University. The pragmatic approach of the RCMP Forensic Identification Unit, which mixes scientists with police officers, underlies its success. "Sometimes it's the practical, even inelegant, solution that works because people will use it," she says.

Margret Brady is an Ottawa science writer.

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