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The technological frontier: New forensic tests helping to solve cold cases

Rachel Goldberg, Forensic Technologist at the Centre of Forensic Sciences, loads samples in Toronto on Wednesday, March 23, 2016.
Image Credit: THE CANADIAN PRESS/Frank Gunn
June 09, 2016 - 9:00 PM

TORONTO - In a spartan room in north Toronto, a woman dressed in long-sleeved scrubs — her face hidden behind a paper mask and a hairnet over her blonde hair— slips on gloves and examines a pair of faded jeans.

Her face inches from the jeans, she peers closely at the markings on the denim under a special lamp meant to simulate daylight, occasionally swabbing them with filter paper, then applying chemicals to the paper.

When it fails to change colour — signifying there's no blood there — she throws the paper away.

Every day, technologists at the Centre of Forensic Sciences pore over items retrieved from crime scenes across Ontario, looking for blood stains, saliva or semen from which to extract DNA.

Though they know the broad strokes of the case, their work is "solely focused on examining the items," said Jack Laird, who heads the centre's biology department.

"We deal with cases that are shocking really, frankly, every day and that's the role, that's the work," Laird said. "Our role is to objectively examine the evidence."

The centre, which operates independently from police, provides tests free of charge to support all official investigations in Ontario.

Forensic tests, including new developments like genetic phenotyping that can reveal physical features such as hair and eye colour, have become a go-to for law enforcement over the last few decades.

The same tests routinely conducted in today's investigations can also help crack long-stalled cases. For detectives toiling to solve hundreds of cold cases, increasingly sophisticated technologies are powerful tools that can reveal previously unattainable — and often pivotal — clues.

But not every criminal leaves DNA behind, or in a sufficient quantity. Evidence wasn't always handled as carefully as today, or stored in the best conditions. And even if a profile emerges, it may not point to a suspect.

"The fundamental approach to the case is the same as it is in every case," Laird said. "What's different though, by virtue of the passage of time and the changes in standards over a long period of time, is that sometimes we have to look out for additional limitations that our results might come with on a cold case."

Forty years ago, he said, when police collected evidence, they couldn't apply the same sort of anti-contamination measures that arrived with the DNA era.

"There was no anticipation that one day we would be dealing with tests as sensitive as they are today."

Canadian police forces began using DNA tests in the early 1990s, but only rarely because the procedure was pricey, time-consuming and used up the entire biological sample, said Brian Borg, the former head of Toronto's cold case squad.

In the mid-90s, new technology called polymerase chain reaction, or PCR, allowed tests to be conducted on much smaller samples, he said.

The real turning point, however, came in 2000 with the launch of the National DNA Data Bank, which brought together DNA samples from crime scenes across the country, Borg said.

What had previously been a manual process, requiring officers to spot similarities between cases and request a comparison, suddenly became automated, Borg said.

Officers began entering DNA profiles to see if any connections could be made, he said. They also requested samples from offenders imprisoned before the data bank came into effect.

"Since then, there's a lot of cases that have been solved through the National DNA Data Bank," he said.

One of the first cold cases solved was the murder of Muriel Holland, 63, who was raped and killed by a man who broke into her apartment in Mississauga, west of Toronto, in 1991.

DNA from the scene was added to the data bank and six months later, there was a link to the profile of Richard Eastman, a dangerous offender behind bars on a separate sexual assault. He was charged and later convicted of first-degree murder.

Years can pass without a match, however. In 2000, DNA evidence showed the same person was behind the killings of Susan Tice and Erin Gilmour, two women sexually assaulted and murdered in their homes four months apart nearly two decades earlier. But police have yet to find to whom that DNA belongs.

Their killer may have stopped committing crimes, or is already behind bars on a crime that doesn't require a DNA sample, Borg said. He may simply have moved out of the country or died, he said.

A similar system exists for fingerprints. The Automated Fingerprint Identification System compares finger and palm prints from people who are charged with crimes with those of known offenders or found at crime scenes.

New developments in DNA and fingerprinting technology have allowed investigators to revisit cases where such tests had been ruled out, experts say.

Today's methods are able to detect fingerprints that would previously have gone unnoticed, and to do so on surfaces that were not amenable to testing in the past, said Brian Dalrymple, a retired forensic analyst for Ontario Provincial Police now working as a consultant.

Dalrymple, who introduced the force to the use of laser in fingerprint detection in the late 1970s, said that discovery kicked off a wave of research that has led to several new techniques that target the various fingerprint compounds.

Many rely on fluorescence, in which a substance absorbs a specific wavelength of light and emits a light of a different wavelength, he said.

Before that, investigators were limited to staining fingerprints with powders or chemicals such as ninhydrin, which reacts with amino acids.

Likewise, the newest DNA technology is able to extract more information from samples previously considered too small to analyze, said Anthony Tessarolo, director of Toronto's Centre of Forensic Sciences.

Current tests require about a nanogram of DNA, roughly what you would get if you smashed an M&M candy into a billion pieces. A small stain is enough for multiple tests.

Even so, sometimes there isn't enough material to test, Tessarolo said. Occasionally, the DNA has degraded after being exposed to moisture or high heat.

Since DNA testing destroys the sample, it's important that the timing be right, he said.

"If we're on the edge of implementing new technology, we have to ask ourselves whether it's best to proceed with testing now or to wait until that new technology has been validated and implemented," he said.

"It's a question that we'll have to ask ourselves over and over because once that new technology is implemented, there's going to be another one coming down the road."

As technology continues to evolve, so will police investigations, Tessarolo said.

"Another 30 years from now, I have no doubt that investigators will be coming back to cases that we're working on right now and asking the same question: 'What new technologies are available in forensic science that could move this case forward, that could take this from a cold case to a solved case?'"

News from © The Canadian Press, 2016
The Canadian Press

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