Police sketch created with DNA technology is potentially useless or even misleading, says scientist

Police sketch created with DNA technology is potentially useless or even misleading, says scientist

Calgary police hired a U.S. biotech company to create a picture of a woman using only her DNA, but a scientist says the evidence behind the technology to create the image simply isn't there. 

On Christmas Eve, a newborn girl was found in a parking lot in the northwest Calgary neighbourhood of Bowness.

Police said it's not yet known whether the child was already dead when it was placed in a dumpster. 

Evidence at the scene suggested the mother might have been in medical distress, but police have since run out of leads to try and track her down.

Parabon NanoLabs, the Virginia-based company that created an image of what the baby's mother could look like, used DNA phenotyping to create a composite sketch through a program it calls Snapshot.

The genetic evidence was collected at the crime scene, extracted to create a DNA profile, and then that genotype data was analyzed to produce a report that included the woman's likely hair colour, eye colour, skin colour, face shape and ancestry, among other traits. 

Those features crafted from statistical models that correlate genes with physical traits, were then used to create a composite image.

Parabon created images of what the woman might look like at age 18 and 25, since her actual age is still unknown. 

Benedikt Hallgrímsson, a biological anthropologist and evolutionary biologist who studies the significance of phenotypic variation and variability at the University of Calgary, said he wouldn't recommend phenotyping be used as a regular technique by law enforcement. 

"I think the evidence is not there to support the use of this technique. If you were to poll experts in the field, people who work in this area, there are very few who believe that this is feasible," Hallgrímsson said Thursday.

Hallgrímsson said the risk of these composite images is "twofold." First, the image might lead to someone being falsely accused of a crime. Second, the actual suspect might not look anything like the picture and could be overlooked. 

"It's dangerous to oversell science. It's dangerous to tell people that science can do something that it can't do, because when it becomes clear that it's not capable of doing that then it undercuts faith in science."

In an interview with CBC Calgary News at 6, Ellen Greytak, the director of bioinformatics at Parabon, said the composite is meant to be a general snapshot of what the person may look like, not a photo-realistic image. 

Once the program has created a shape of the face, forensic artists then fill in the eyes nose, mouth and other features as best as possible.

One real challenge they face, said Greytak, is knowing how old the person is.

"Because that's not written in your DNA sequence, you have the same DNA sequence when you're born through the rest of your life," she said.

To mitigate that, the face created is of a young adult with a normal body weight and artists can work to age them if needed, or make them look younger.

Lab charges $3,600 for each profile

The lab's turnaround time is approximately 45 days from the day it receives its sample. It charges $3,600 US for each profile, which includes the lab work, analysis, report and composite, a Parabon representative said in an email.

On its website, Parabon said that it currently only provides the service to law enforcement agencies.

There have yet to be any studies of Snapshot's effectiveness published in a peer-reviewed journal.

The Parabon representative told CBC News that a scientific paper on Snapshot is forthcoming, and pointed to a recent paper published in the Proceedings of the National Academy of Sciences that demonstrated that phenotype predictions can be used to identify individuals. 

However, that paper's conclusions have been criticized by some members of the genetic science community, including one of the paper's co-authors who told Nature that the paper "misrepresents" his findings, and tweeted that the predictions weren't accurate.

Snapshot predicted that the Calgary mother is likely of northern European or native North American descent.

Any services trying to pinpoint ancestry through DNA — from Snapshot to companies like 23andMe —  rely on markers gathered from large databases like Stanford's Human Genome Diversity Project and The International Genome Sample Resource. 

Ancestry services like 23andMe and AncestryDNA have received criticism for having smaller numbers of people of First Nations or Asian heritage in their databases compared to European populations, which has led to less certainty or specificity when pinpointing the heritage of someone of, for example, Inuit descent, as opposed to someone whose ancestors are from Ireland.

For example, AncestryDNA's reference population includes 232 samples from Scandinavian people, 432 from Eastern European people and just 131 from Native Americans — which include First Nations people to people of Mexican ancestry. 

"If the evidence for this kind of prediction is not good, then you would question the use of public funds to pay a company to provide you with information that is not just potentially useless but even potentially misleading," Hallgrímsson said. 

The company states on its website that Snapshot has been used in hundreds of cases around the world. It lists eight cases that have been released publicly where the technology was used and it led to arrests. In two of those cases, the suspect was found guilty. The others are still before the courts.

Hallgrímsson said the genetic markers that determine facial features are "extraordinarily complex," and that if he had to put a number on it, he would estimate that scientists could predict skin colour with 25 per cent accuracy — and that the precision of predicting a person's face shape would likely be much lower. 

"We know very little about the genetic variants that determine the shape of the face or features like the shape of your nose or the shape of your cheeks or the height of your face, or the width," he said. 

Image is simply an approximation: police

On Thursday, police reminded Calgarians that the composite image is simply an approximation. 

"We want to remind citizens that the image shared is not a photograph, but a scientific approximation of what the mother may look like," police said in a Facebook post.

Calgary police also said that they have received questions about why they haven't shared information or a composite of the baby's father. Police said that as they don't have the father's DNA, they can't complete a phenotype for him as they did for the mother. 

Police said since releasing the image, they have received approximately 30 tips. 

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