To catch a criminal, police sketches can be useful — or hilarious

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They say a picture is worth a thousand words, but are police sketches worth the paper they're drawn on?

Twitter users played a gleeful game of Guess Who yesterday, with an artist's impression of the man who Stormy Daniels alleged threatened her in 2011. The adult film star says she was being warned off selling a story to a magazine about a sexual encounter with Donald Trump.

Tom Brady and Matt Damon were among the celebrities being compared to the sketch on social media, but for Diana Trepkov, one of Canada's top forensic artists, it's a serious business.

"Someone knows something, always, when it comes to stuff like this," she told The Current's guest host Laura Lynch.

"If someone did threaten [Daniels] seven years ago, they would be bragging about it in a bar to some friends," she added. The sketch could ring a bell and prompt them to come forward. Daniels, whose real name is Stephanie Clifford, is also offering a $131,000 US reward to anyone who can positively identify the suspect.

Trepkov has worked on more than 200 cases worldwide. She said that when someone is threatened, "that image will burn in their head, they'll they'll remember that face."

When working with victims, she starts by asking questions that could trigger that memory: What was the weather like that day? What was the person wearing?

Once a witness is comfortable, she'll show them a picture catalogue of features: eyes, noses, ears. The witness will point out what resembles the perpetrator, and Trepkov will start to draw, but without showing the witness her progress.

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When she is about 60 to 70 per cent finished, she will "swoosh it" past the witness, giving them only a brief glimpse.

"I could tell by the expression on her face how close I am," she said.

"If it's a little 'Oh my God,' or a scared look, then I know I'm getting close."

Our memories make mistakes

Michael Arntfield, a criminology professor at Western University, cautions that human memory can be fraught with problems, which can make for unreliable police sketches.

"We don't remember explicit details necessarily, certainly not the degree of detail that courts like to hear," he said. "We remember with emotions, we remember with … other senses, including scent and sound."

Arntfield said that in the 1950s, U.S. firearms company Smith and Wesson released the Identi-Kit, a collection of facial features printed on transparent sheets.

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"Essentially it's a Mr. Potato Head," Arntfield explained, "where you have a face, and just plot certain eyes or nose or mouth shapes on to this transparency."

"Because it was sufficiently generic, and allowed for a certain degree of interpretation ... it really resonated with people."

In contrast, the sketch commissioned by Daniels has an "excess of detail," he said, and is more likely to generate publicity than leads.

A useful tool (with a credible witness)

The wrongful murder conviction of Thomas Sophonow is an example of how unreliable eyewitness accounts can be, said Arntfield.

In 1981, witnesses incorrectly identified Sophonow as a man they had seen near the Winnipeg donut shop where 16-year-old Barbara Stoppel was murdered. After three trials, he spent four years in prison before being acquitted.

As an investigative tool it can useful, he said, but only with a credible witness.

Trepkov has come across fabrications in her work, and has learned that witnesses that are too ready to accept her sketches are often hiding something.

"When someone says it's 100 per cent, and you don't have to fix anything," she said, "then it was made up."

Listen to the full conversation at the top of this page, where you can also share this article across email, Facebook, Twitter and other platforms.

This segment was produced by The Current's Julie Crysler, Howard Goldenthal and Exan Auyoung.