DNA expert testifies at Justin Dumpfrey murder trial
Drops of blood found in Justin Dumpfrey's apartment and on some items tossed in the garbage contained DNA over a trillion times more likely to belong to Holly Hamilton than a random other person, court heard Monday.
Dumpfrey is charged with second-degree murder in the death of Holly, his on-again, off-again girlfriend and mother of his daughter. Holly was 29 when she disappeared on the night of Jan. 14, 2018. Her stabbed and frozen body was found in the trunk of her car three days later.
DNA experts will never say DNA is an absolute match, explained Joanne Cox, a forensic scientist at the Center of Forensic Sciences (CFS). That's because they don't have DNA profiles of every person on the planet with which to compare.
Instead, forensic scientists look at whether a person's DNA can or cannot be excluded. If it can't be excluded they look at what is called the likelihood ratio."
For instance blood was found on a piece of wood trim from Dumpfrey's apartment found in the garbage. DNA from that blood was 160 trillion times more likely to belong to Holly than someone else not related to the 29-year-old, Cox said.
Similarly blood found on the exterior door on the east side of 1510 Barton St. E. also had DNA 160 trillion times more likely to belong to Holly.
Other likely matches were found on drops of blood on the laminate floor in Dumpfrey's basement unit, a cabinet outside the bathroom, a container of body wash, Holly's keys (also found in the garbage next door) and a cloth.
However, in some of those samples, including on the floor in the kitchen and bathroom, there were at least one other DNA also present. In some of those cases, the sample was too small to test. In others there was a strong likelihood it belonged to Dumpfrey.
It's not clear if the DNA likely from Dumpfrey was from blood, or another source of DNA (bodily fluids, skin cells). Cox said it's not uncommon to find DNA from other people in high-traffic areas such as a bathroom floor. There is no way to tell when that DNA was deposited, including whether it was before or after the blood.
Cox also explained how scientists tested fingernail clippings from Holly after her autopsy. A male DNA was detected and Dumpfrey's DNA could not be excluded." How the DNA ended up under her fingernails was not clear.
They also tested Dumpfrey's clothes after his arrest that had drops of blood on them. But none of the blood drops came from Holly. Some were likely to come from Dumpfrey and other DNA was an unknown male.
Court has already heard from the forensic officers who collected evidence in the homicide investigation. Not all evidence was accepted for testing, this included just 12 swabs of bloodstains being tested.
Cox explained that the CFS couldn't possibly test all items from every case across the province. It's not just an issue of resources, but also of strategically testing items that have value to the investigation.
The trial continues Tuesday.
Nicole O'Reilly is a crime and justice reporter at The Spectator. noreilly@thespec.com