A student in the San Francisco Bay Area reportedly used Snapchat's gender swap filter to take down a police officer allegedly looking for an underage hookup on Tinder.

Ethan, who's 20, took a photo of himself and used the feature to pose a teenage girl named "Esther" as way to hunt predators, NBC Bay Area reported on Tuesday.

The fake profile said Esther was 19, which apparently caught San Mateo Officer Robert Davies' eye on Tinder.

They moved the conversation to Kik Messenger and Snapchat, CBS News noted.

Ethan told Davies he was 16, but this allegedly didn't bother the officer and their messages "got a lot more explicit" as they talked for more than 12 hours.

The student then sent screengrabs of the conversations -- taken in Airplane Mode because Snapchat alerts you when a screenshot taken -- to Crime Stoppers, according to NBC Bay Area.

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