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Focus: Canadian investigator completes innovative DNA research

Diane Cockle tracks progression of human decomposition at crime scenes
|Written By Charlotte Santry

Sgt. Diane Cockle has inspected mummies, puzzled over pink-toothed corpses, and been labelled a white witch over the course of her career as a forensic investigator.

‘People say I have the grossest job,’ says Diane Cockle. Photo: Greg Ehlers, Simon Fraser University

Having worked in Rwanda, post-tsunami Thailand, and Haiti, as well as on the infamous pig farm murder case in British Columbia, it’s fair to say she gravitates towards unusual situations.

“People say I have the grossest job,” says Cockle as she describes her work with the Royal Canadian Mounted Police’s national forensic identification support services.

Her gruesome role has helped her produce the world’s first comprehensive study of the progression of human decomposition at crime scenes.

Cockle hopes her doctorate from Simon Fraser University will help police to determine the location of murders and prevent miscarriages of justice.

The standard forensics textbooks use research carried out in places like Tennessee where humidity levels are very different from those in Canada.

Cockle’s research demonstrates that these different humidity levels mean bodies decompose at different rates and that, despite what TV shows such as CSI would have us believe, there’s no standardized way of accurately stating how long someone has been dead.

“That’s one of the big results from a legal perspective,” says Cockle. Police will no longer be able to rely on strict formulas for postmortem interval that measure the time elapsed since a person has died. The numbers have “a big impact in court,” she says.

Her research also identified differences between bodies that have decomposed outdoors and those that have rotted inside.

“One of the issues I had at a crime scene was where we found a body by the riverbank,” she says.

“We had no idea whether the body had come in from the water or been dumped there from the land.”

She hopes the information will alert police to the fact that there may be a second crime scene.

Cockle also tried to differentiate between natural and man-made traumas found on corpses. For example, when could injuries be the result of normal decomposition or animals scavenging the person’s body as opposed to being the work of another human?

Cockle says her work could “absolutely” lead to dropping the charges against suspects.

She highlights the case of Louise Reynolds, the single mother charged with second- degree murder after an autopsy report suggested someone had stabbed her seven-year-old daughter more than 80 times with scissors.

Authorities dropped the charges after Reynolds had spent 22 months in custody when evidence came to light that strongly suggested a dog had mauled the child.

Cockle’s unique research was possible due to her police role that gave her access to several hundred homicide files containing crime scene photos.

She’s an expert in all aspects of crime scene investigations but specializes in the recovery and analysis of human remains from crime scenes.

Her interest in decomposition arose in part during a trip to Thailand after the 2004 tsunami to help identify victims.

She noticed people decomposed very quickly in Thailand and “all the victims had pink teeth.”

After looking into what could be causing this odd phenomenon, she found that drowning caused the blood vessels in the teeth to burst. “I didn’t know that before and nobody else did,” she says.

The experience cemented her belief that Canada needed its own research that took into account environmental factors affecting decomposition.

Towards the end of her doctorate, she travelled to Haiti to identify victims of the 2010 earthquake and was again shocked by what she found.

“All of that dust and concrete in the buildings had sucked the moisture out of them and turned them into little mummies . . . preserving them.”

Her most dangerous escapades have been in Rwanda while working with the RCMP’s Canadian war crimes section to investigate the claims of asylum seekers who land in Canada claiming they suffered human rights abuses in their home country.

“The Canadian team were the first ones to do this, to use forensics to substantiate the witness statements,” she says.

The results weren’t what she had expected. Her team found out that some refugees, far from being innocent victims, had participated in the 1994 genocide of the Tutsis by the Hutus.

Cockle explains in her soft, slightly Scottish lilt: “We were going after one of the big guns, one of the most important people in this district that ordered the deaths of people. I was asked to go to a village where we knew these two women had been killed, find the unmarked grave, and do trauma analysis to substantiate the statements that the villagers had provided, which was used for the prosecution of one particular bad guy.”

In a rural part of Rwanda where skirmishes were going on and the only families left were Hutu, it was undoubtedly risky work.

“The villagers were quite concerned that we were there to punish them. They actually called me a white witch,” says Cockle.

“They saw me directing the investigation, doing the autopsies, and looking at the bodies, and they were actually worried that I was going to poison the water.”

She adds: “Towards the end, we were worried because some of the men were drinking their fermented beer drink, their banana beer, and getting rowdy, and . . . the feeling had become more hostile, so we had to pack up what we were doing and leave in a hurry.”

That was Cockle’s second trip to the country. Her final visit involved reconstructing an entire village, a task she was highly qualified to do having initially trained as an archeologist.

There was a problem, however. “The problem was we were working on a hill right near the Congo border and were worried that we were huge targets — [I’m] blond, female — for being kidnapped.”

Despite her matter-of-fact-tone, she admits to feeling “a bit vulnerable” without a gun or even cellphone coverage.

Besides her international experience, Cockle has worked on the biggest forensic case in Canadian history involving B.C. pig farmer Willie Pickton.

“We moved more dirt on that farm than they did in Ground Zero,” says Cockle.

“It was probably the most complicated crime scene that anyone had worked on and really changed the way we do forensics in Canada,” she adds.

The majority of evidence came from DNA rather than bodies, and investigators decided to divide crime scene areas into grids in order to analyze every possible speck of genetic material. Cockle spent a month examining Pickton’s cutlery. Was it worth it? “I didn’t find anything,” she confesses.

Her detail-oriented work clearly demands an extraordinary ability to concentrate.

“We all have our pencils ordered by size and we’re all obsessive compulsives, and that’s what makes the best crime scene investigator,” she says with a laugh.

But all of that gore must be emotionally demanding, too, at times. Does it take its toll? She responds: “Some of the files over the years have created little scars, but you build up a bit of a professional callous.

“But the day that you stop caring about it, you really need to walk away. You need to be impacted in one way, but not too much so that it incapacitates you.”

Her next research project will involve heading to the Yukon to see how human remains decompose in Arctic environments.

There’s still much to learn about forensics, she emphasizes, highlighting the discovery of chimeras — people who have two sets of DNA because they came from two fertilized eggs that merged in the womb.

“Somebody could lick an envelope and leave one DNA profile and bleed on that same envelope and leave a different profile,” she says.

“We think that things like DNA are ironclad, but they may not be,” she adds.

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