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Colby Cosh: The wonders, and dangers, of DNA detective work

Toronto Police Chief James Ramer discusses new evidence in the case of the 1984 murder of Christine Jessop, on Oct. 15.
Toronto Police Chief James Ramer discusses new evidence in the case of the 1984 murder of Christine Jessop, on Oct. 15.

Last Thursday, the Toronto police announced a decisive solution to one of Canada’s most heartbreaking cold homicide cases: the 1984 abduction, rape and murder of nine-year-old Christine Jessop. This was the crime for which the innocent Guy-Paul Morin spent nearly eight years in jail; Morin was ruled out as a suspect by DNA evidence and exonerated in 1995. But it was to be another 25 years before the development of methods of genealogical crime investigation allowed someone else, a friend of Christine’s family, to be ruled in.

With astonishing speed, police forces have learned to exploit cheap gene sequencing and open personal-genome databases to crack cold cases. The key is that some of these gene databases are uploaded by amateur enthusiasts with fairly extensive family trees attached, allowing investigators to identify ancestors, cousins and descendants of people who left DNA traces at the scene of a crime.

In theory, you might not even need to approach the identity of a suspect through relatives, although this technique has already been responsible for a number of startling investigative successes: DNA potentially offers enough non-familial information to narrow down a limited universe of suspects. But the family tree method, mostly developed by amateur genealogists, is the one making headlines right now.

On Monday, investigative genealogy scored another surprising victory in the United States, thanks to an Ohio-based non-profit called the Porchlight Project. This case surrounds a partial skeleton that turned up in an old garage in the Ohio village of New London in 2016. The garage belongs to a former mayor of the place, but the remains were obviously very old (there was no evidence on the skull of any dental work whatsoever) and the building had been unused for a long time. Ordinary anatomy suggested that the bones had belonged in life to a small young woman, probably a teenager. that is as far as anyone could get using classical techniques of pathology.

The DNA from the skeleton was decoded and the data were given to one of the project’s affiliated genealogists. They soon constructed a family tree and concluded that the only plausible owner was a young teacher named Hallie Armstrong — who had perished from “unknown” causes in 1881, aged 18. No other known member of this family, from any era, makes a possible match. But this led immediately to a second mystery. Armstrong’s date of death is known because she already has a grave in Wilmington, Ohio, two hours’ drive from New London.

The project’s best guess is that the young woman did die naturally — and had her corpse hijacked as an anatomical specimen, which was not uncommon in the 19th century. There is evidence that her bones have been subjected to dissection with power tools, and the past owners of the garage include an old-time chiropractor. But who, or what, is in the other grave?

Porchlight Project founder James Renner writes that, “The old plot is in a location that would make exhumation difficult — the ground is hardened and a large tree has sunk its roots around her grave. A caretaker probed the ground but could not reach deep enough to make contact with a casket, if there is one.”

The story may therefore remain unsatisfyingly incomplete, but at least one village has been lightened of the burden of unidentified human remains. Helping the innocent sleep easier, one way or another, is the paramount goal of genealogical crime investigation. The Porchlight Project has identified living relatives of Hallie Armstrong, but none have yet been near enough to provide useful background information that might help sort out the confusion.

Privacy experts are beginning to squawk about genealogical crime-solving, noting that the people who have made their DNA code public are exposing relatives to possible police suspicion. They observe correctly that if you send your DNA in to a commercial service, or to one of the noncommercial open-source ones that have proved most fruitful in detection, you are giving strangers access to information about your unsuspected and very distant relatives, or even hypothetical ones not yet born.

They also acknowledge that the information is fantastically reliable. If the privacy of relatives is a decisive consideration, one must conclude, perhaps with an apology to Guy-Paul Morin and all the other innocents DNA sequencing has liberated, that it is forbidden for anyone to read a genome — even his own. Your own genome, after all, tells you stuff about your relatives. (You might find out, as people do all the time, that your father or grandfather wasn’t who you thought it was.) And if you “own” the information in your DNA, one implication of ownership is that you can share, sell or trade that information. If it is somehow the common property of a family, you would surely need your family’s permission to transmit or even to interpret it.

Any investigative method can and will be abused by police, but triumphs like the Jessop and Armstrong cases put me in mind of the period when astronomical spectroscopy was discovered. Philosophers had been certain, and testified to their certainty up until the last minute, that nobody would ever be able to discover the physical composition of the stars without somehow visiting them. Within a matter of months, mostly because the manufacture of optical prisms had improved, humanity knew a lot more about the makeup of the Sun than it did about that of the Earth. Science is not to be underestimated.

National Post

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