LOS ANGELES (CBSLA) – During her show at the Rose Bowl earlier this year, singer Taylor Swift used facial recognition on her fans, unbeknownst to them, in order to try and screen for stalkers.

At the May 18 show, Swift’s team used a facial recognition camera at a kiosk in the Rose Bowl which was playing clips of Swift’s concert rehearsal, according to a report in Rolling Stone this week.

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While fans were standing at the kiosk watching the videos, a camera inside was snapping photos and sending it to a command post in Nashville, which was cross-referencing it with a database of known Swift stalkers.

“Everybody who went by would stop and stare at it, and the software would start working,” Mike Downing, chief security officer for the Oak View Group told Rolling Stone. The Oak View Group is an advisory board for concert venues.

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Swift’s representatives did not respond to a request for comment from Rolling Stone.

On April 8, about a month prior to the concert, a 23-year-old homeless man was arrested for trying to trespass at Swift’s Beverly Hills mansion.

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On April 14, a Colorado man who police said was carrying a knife, rope and ammunition was also arrested outside the same Beverly Hills home on suspicion of felony stalking. He allegedly told police he had driven from his Colorado home to see the singer.