After the New York Police Department was at a loss when its facial recognition software didn’t turn up any matches, the department decided to get creative with celebrity photos.

According to a report published by Georgetown Law Thursday, in one case police had a partially obscured image of a suspect, but after running it through the software there were zero matches. Then one detective working in the “Facial Identification Section” noticed that the image wasn’t far off the actor Woody Harrelson.

So the detective downloaded a high-quality image of the actor and ran that through the algorithm and, lo and behold, there was a match – but not of Woody. The person who did match with the “Natural Born Killer” was eventually arrested for petty larceny.

This is the reverse of those entertainment websites that tell you which celeb you most look like, although the match is often far from true. Apparently detectives have done this before, sometimes editing the photo.

“Woody Harrelson is not the only celebrity to stand in for a suspect wanted by the NYPD,” said the report author Clare Garvie, a senior associate at the Center on Privacy and Technology. “FIS has also used a photo of a New York Knicks player to search its face recognition database for a man wanted for assault in Brooklyn.”

The Harrelson doppelganger incident took place two years ago, but the report is part of an investigation by the center into how this technology is being used and how it could be misused. It follows San Francisco’s banning law enforcement from employing facial recognition software this week.

“It doesn’t matter how accurate facial recognition algorithms are if police are putting very subjective, highly edited or just wrong information into their systems,” said Garvie. “They’re not going to get good information out. They’re not going to get valuable leads. There’s a high risk of misidentification. And it violates due process if they’re using it and not sharing it with defense attorneys.”

In a statement issued to The Verge, the NYPD said that no suspect has ever been arrested purely as a result of a facial recognition match. “As with any lead, further investigation is always needed to develop probable cause to arrest,” said the department. “The NYPD has been deliberate and responsible in its use of facial recognition technology.”

The worry is the well-documented bias and false positives, with supporters of the technology stating when it improves the critics will be placated. Garvie disagreed, saying, “Improvements won’t matter much if there are no standards governing what police departments can feed into these systems. In the absence of those rules, we believe that a moratorium on local, state, and federal law enforcement use of face recognition is appropriate and necessary.”

Image: Georgetown Law Center