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Inside a police station house in Queens about a year ago, St. Clair Steward insisted he had not been involved in a recent shooting. Mr. Steward told the police he had been resting at home.

Investigators did not believe him. The motive behind the shooting was a mystery, but the victim had combed through pictures of people with past arrests and identified Mr. Steward, a father of eight, as the assailant.

To the detectives involved, the shooting in January 2018 was just the latest in a long line of crimes solved by asking a victim to search through mug shots, an investigative technique used in New York City for more than 150 years. Detectives enter a description of the perpetrator into a database, which then spits out dozens or even hundreds of matching photos. The witness scrolls through, in hopes of recognizing the culprit.

But these open-ended photo searches also increase the likelihood of ensnaring an innocent person, according to studies and experts in eyewitness identification. The method has few safeguards to protect against a false identification and can lead police to focus on the wrong person from the outset of an investigation.