The viral success of Snapchat's gender-swap filter doubled downloads of the app after its introduction in May. Some trans users have criticized the filter, but it also enabled one college student to catch an alleged sexual predator who turned out to be a cop.
According to NBC Bay Area, 20-year-old San Francisco area college student Ethan (whose last name was withheld for his privacy) used the filter to pose as an underage girl online. He was inspired to go catfishing for predators after one of his friends told him they were sexually abused as a child, Ethan told NBC.
Using Snapchat's gender-swap filter, he took a photo of himself swapped as a girl, and set up a Tinder profile with the name "Esther." A man messaged him there, saying, "Are you down to have some fun tonight?"
"I decided to take advantage of it," Ethan told NBC.
That man turned out to be Robert Davies, an officer for the San Mateo Police Department.
Ethan moved their Tinder conversation to Kik messenger, and then Snapchat's direct messaging, according to CBS, where the tone became more explicit. "Esther" told Davies that she was 16 years old, and asked if that bothered him. He said it didn't, according to police who saw screenshots of the conversation.
The pair texted for over 12 hours. Because Snapchat notifies the other person when someone takes a screenshot of their conversation, getting evidence to send to authorities was tricky. Ethan said he had to turn his phone on airplane mode before taking several screenshots at once, to avoid the platform alerting Davies and possibly being blocked.
He sent the screenshots to the local police department's tip line, and Davies was arrested on one count of communicating with a minor for the purposes of committing a felony.
"While the criminal investigation is still running its course, this charge, if true, is disturbing and the conduct alleged violates the very values and principles of this department," a spokesperson for the San Mateo police department told Motherboard in an emailed statement.
“This alleged conduct, if true, is in no way a reflection of all that we stand for as a Department, and is an affront to the tenets of our department and our profession as a whole," San Mateo Police Chief Susan Manheimer said in the statement.
Davies is currently on paid leave, according to the San Mateo police department.
This article originally appeared on VICE US.