Genetic genealogy offers new tool for solving old crimes
DNA points investigators in right direction
David Mittelman says one of the most critical tasks in cutting- edge genetic forensics is to not destroy the evidence.
“There’s low quantities sometimes, there’s not a lot of evidence left. The last thing you want to do is consume evidence without getting as much information as you can get,” said Mittelman, the CEO of Othram Inc.
“Our goal is to get the most information from the evidence without consuming it.”
Othram, a Houston, Texas forensic service, was behind the research that helped the Toronto Police Service close in on the suspect in the 1984 murder of Christine Jessop, who was just nine years old when she vanished north of Toronto.
Her body was found two months later, some 50 kilometres away in Sunderland, Ont.
She had been sexually assaulted and killed. Three decades later, semen that was found on her body was used to piece together a picture of who the killer might have been. On Thursday, Toronto police named their suspect: Calvin Hoover, who was 28 at the time of the crime.
He’s been dead since 2015, and police said on Thursday that they finally made the DNA match on Oct. 9, through genetic genealogy, 36 years after Jessop went missing.
The big break came over roughly the past year, when investigators, including Othram, worked with the DNA found on Jessop’s body to identify Hoover.
Othram did the laboratory work that helped unlock DNA evidence that was used to pinpoint Hoover; much of the rest was done by the Toronto police and the Centre for Forensic Sciences in Ontario.
“We focus on cases that have failed other testing methods, have been unsuccessful at producing answers,” Mittleman said. “And we try to pull as much information as we can from this evidence to help investigators do more work.”
When it comes to historical DNA, Mittelman explained, it can often be degraded, or there might be very little of it. In the case of sexual assault victims, there are different DNA strains mixed, and bacteria, over time, can interfere with DNA.
“We can handle very degraded DNA, we can handle very low- quality DNA,” said Mittelman.
While conventional DNA techniques often need clear samples in larger quantities, and look at a small number of “markers” across the DNA, Othram uses thousands of markers to identify larger groupings of people who share the markers.
Anthony Redgrave is a forensic genealogist who is currently with Redgrave Research, but previously worked at Othram on the Jessop case. He explained to the National Post that conventional DNA testing is usually done with something called short tandem repeats — small pieces of DNA that change rapidly between individuals. STR information could be close in matching DNA, perhaps, between children, parents and siblings.
In the Jessop case, the multiples of markers would be good for broader groupings of several cousins distant.
Once the research team had extracted DNA information, Redgrave said, the team ran the data through GEDMatch and Family Tree DNA, the databases available to law enforcement.
“We form little cluster groups of people who are related somehow,” explained Redgrave.
This points investigators in a direction, Mittelman said, which they can use to track down suspects.
“Genealogy will help you eliminate possibilities, but generally genealogy isn’t getting you an exact answer,” he said.
What Mittelman’s lab does is look at the information they can glean from the samples and then use it to build out a genealogical or ancestral tree to identify broader families to which the DNA might correspond.
“We find these genetic relatives that share some of these markers,” Mittelman said. “You can essentially thread an unknown person on a family tree and figure out candidates for who they might be.”
Toronto police used the two “families” identified in
YO U CAN ESSENTIALLY THREAD AN UNKNOWN PERSON ON A FAMILY TREE.
Othram’s research to work backwards, building out a list of relations before coming across a suspect. The information Othram unlocked from the unknown semen was then used alongside a blood sample that the Centre for Forensic Sciences had on file to produce a DNA match: Hoover.
When Hoover died, in what police called “non- suspicious circumstances,” an autopsy was done. The Centre for Forensic Sciences still had a DNA sample from that autopsy. It was that sample that was used to compare with the DNA information from Othram.
Toronto police called the new technique an “investigative tool,” versus evidence. In the end, they still had their investigative work to do and found Calvin Hoover had a connection to the Jessop family, they were acquaintances, and Hoover had been in the Jessop home.
The Jessop case is by not the only cold case solved with such t echniques. In 2018, Joseph James Deangelo — the Golden State Killer — was arrested in California as the suspect in dozens of rapes and 13 killings. Deangelo was sentenced in August.
He was found because crime scene DNA corresponded to DNA matches on Gedmatch, the genetics database.