Every couple of months, Officer Michael Zinn of the York Area Regional Police Department in Pennsylvania ran a photo of a man through the department's facial recognition software. In a year and a half of searches, the result was always the same: No hits.

The man was a suspect in the July 2016 sexual assault of a 15-year-old, but his identity remained a mystery. The photo came from the cellphone of the victim, who had exchanged text messages and pictures with the suspect before the assault.

Then last December, Zinn ran a search again, comparing the man's picture with database