How DNA and a genealogy website helped lead to the killer of Christine Jessop
|Toronto Star 16 Oct 2020 at 05:59|
It was DNA evidence that exonerated Guy Paul Morin in the slaying of nine-year-old Christine Jessop in 1995 — but it would take another 25 years for genetic technology to home in on her killer.
In a stunning development Thursday, Toronto police announced homicide investigators identified now-deceased Calvin Hoover as the man who killed Jessop, the girl from Queensville, Ont., who was abducted then fatally stabbed in 1984.
The long-sought identification was made using genetic genealogy — an emerging investigative technique that’s risen to prominence through recent arrests in high-profile U.S. cold cases, but that’s only just starting to be used in Canada.
“It’s a very useful tool in murder investigations such as this one,” Toronto police acting Staff Supt. Peter Code told reporters Thursday.
The enterprising technique , after police in California arrested the so-called Golden State killer — a man responsible for a string of cold-case murders — through a combination of a historic DNA samples and a free public genealogy site.
In essence, the technique allows investigators who have a DNA sample from a crime scene — semen or blood on a victim’s clothing, for instance — to plug the sample into a database of hundreds of thousands of others. This allows police to cross-reference the crime scene DNA to genetic profiles submitted by the scores of people who’ve handed over their personal data to public sites, like GEDmatch, seeking genealogical information.
Police then get what Code stressed was not DNA match but rather a “family tree” — a long list of potential persons of interest, who share common DNA lineage with the sample found on the crime-scene evidence.
From there, police undertake more classic investigative techniques — including interviewing and poring over historical records — to identify a suspect.
“Our perspective in this case is that genetic genealogy is not evidence,” he said. “We are utilizing it as an investigative tool, as a technique that can give us a list of potential persons of interest.”
In the Jessop case, the search for Hoover began with a semen sample taken from Jessop’s underwear. Toronto police investigators submitted the DNA sample to the U.S.-based lab Othram Inc., which is accredited with law enforcement agencies.
David Mittelman, CEO of Othram, said in an interview that the lab began working with the Toronto Police Service last year.
“There was DNA evidence but the DNA had not been used fruitfully in other approaches,” he said. “So we took on the project.”
From there, the company built out “a genealogical profile” — the DNA profile of a family, not an individual — which Toronto police investigators then uploaded to the ancestry site GEDmatch.
Privacy experts have raised concerns about the potential intrusion posed by law-enforcement use of other ancestry sites, like 23andMe or Ancestry.com; Meaghan Gray, spokesperson for the Toronto police, said GEDmatch users have “explicitly given permission for this information to be accessed by law enforcement.”
From GEDmatch, investigators received a list of names: distant relatives of the genetic profile, Gray said.
“This is really new stuff, it was not available a few years ago,” said Mittelman.
From that long list of relatives, investigators narrowed in on Hoover, a neighbour acquaintance of the Jessop family who would have been 28 at the time of Jessop’s death.
“The name Calvin Hoover is one of the names that came up,” Code said.
He did not detail how detectives narrowed in on Hoover from the long list, but said it was via “extensive combing through detailed reports and documents.”
From there, police learned that an autopsy had been conducted on Hoover when he died in 2015 — meaning there was a DNA sample on file with Ontario’s Centre of Forensic Sciences (CFS).
After police obtained a judge’s permission to access the DNA, detectives were able to cross-reference the DNA sample taken from Jessop’s underwear with Hoover’s DNA from his 2015 autopsy.