In 1983, two women were sexually assaulted and stabbed to death in their homes in Toronto, Ont.
Susan Tice was a family therapist and a mother of four teenagers. She was 45 when she was killed in August 1983.
In the same year, in December, Erin Gilmour, 22 year-old aspiring fashion designer and daughter of mining tycoon David Gilmour, was found murdered at her home.
They both lived in the city’s core, just a few kilometres apart. Police said the women didn’t know each other.
There were no suspects.
Seventeen years later, in 2000, using DNA technology, police linked the two murders with the same perpetrator, with the help of trace DNA left by the perpetrator at the scene of the crime.
It was a breakthrough, but the case remained open for many years later with no prospective leads.
A year later, in a separate case, nine-year old Christine Jessop boarded a school bus to go back home and catch up with a friend at a nearby park. The friend showed up, but Jessop never did. She was declared missing, and months later, on Dec. 31, 1984, her body would be found in Durham Region, about 56 kilometres east of her family’s residence. She was abducted from her Toronto home before being raped and murdered.
The Jessops' neighbour, Guy Paul Morin, was wrongfully convicted for the murder in 1980s. He was exonerated in 1995 when new DNA evidence came to light.
In both cases, the real suspect remained at large for years.
Until now.
Almost 40 years later, with the help of DNA technology called genetic genealogy, Jessop's real killer was identified on Oct. 15, and the suspect of the Gilmour and Tice murders was arrested by the Toronto Police on Nov. 28.
Genetic Genealogy
Genetic genealogy is a new technique used in forensic sciences that creates family history profiles by combining DNA test results with genealogical research. It matches a DNA sample procurred at the crime scene to a DNA database, where suspects are narrowed down going through the family history and drawing familial relationships of the DNA samples.
Dean Hildebrand, the dean of the school of computing and academic studies at British Columbia Institute of Technology (BCIT), who has worked in forensics for over 20 years and spearheads the forensics department at BCIT, said the difference between this type of technology and standard forensic techniques is at the end of the process when DNA is analyzed.
He said, in this technique, a next generational sequencing method is used — which generates a lot of information — far more information from the DNA sample than in a standard case, which provides more information to search the genealogical databases and compare it against other samples.
Hildebrand said, "this [technique] is far more labour intensive than a standard DNA analysis."
"First of all, we have to go through all the DNA processing — the extraction, quantification and the amplification and analysis of the DNA."
He added that there are fewer labs to carry out this type of analysis to generate the data needed, causing additional expenses and takes more time.
"Once you have that data there, the police or forensic genealogists will put that data into a database and start to put this together. [They] screen different families. So it can take months to go through this process, depending on the complexity of the search."
He said, the challenge is "even if they've narrowed it down to a family, the next part is that the police have to work their way through all of those members of that family tree." It involves a thorough filtering of potential suspects through the family trees — elimating all the female suspects if they know the perpetrator is a male, then looking at all the people on the tree who might still be alive, looking at the proximity to the victims, and so on.
"After all this," he said, "they have to decide how to get a DNA profile from the actual suspect."
One of the ways is to obtain a search warrant; the other way, he explained, to build a DNA profile of the suspect is for the police to follow the suspect around to get a cast-off DNA sample and compare it against the one they obtained in the beginning at the crime scene. Months of investigating and analysis is needed to narrow down on potential suspects.
It takes longer when the suspect is a first-time offender, as they are not on the offenders list.
The technology and cases that have successfully used this technique
The breakthrough genetic genealogy is a complicated technology, Hildebrand said. Compared to the standard cases wherein the forensic lab can analyze a dozen to a couple dozen positions on the human genome, the new technology involving genetic geneology will analyze hundreds and thousands of positions, he said.
More high-profile cases and complicated cold cases from years earlier have been using this technology to identify the killers — recently, the 1983 Toronto murders involving Gilmour and Tice, Christine Jessop's murderer, the Golden State killer in California, USA, all have used this technology.
The accuracy rate of this technique will depend on the familial relationships of potential suspects, he said. "The more closely related people are, for example, parents and children share far more DNA, the more accurate it will be."
"If your suspect hits on people that look like their parent or child, that's going to be more accurate than if it's hitting on on cousins, second cousins, third cousins or grandparents — so the farther away you get in your family tree, the less DNA you expect to match."
But he said, once a profile of the suspect is obtained, and the profile will match the one from the crime scene, it will be highly accurate because it's a direct comparison — the suspect sample to a suspect sample found at a crime scene.
While the cases might take longer to solve due to the elaborate nature of analysis, it is still a breakthrough in forensic sciences, Hildebrand said. "This is a fascinating field for that next generation of forensic scientists that want to work in forensic DNA. It's really an amazing time to be working in this discipline."
He encouraged the next generation of science students to pursue forensic sciences and put their science skills to use for the benefit of our citizens and society.
