A 20-year-old in the Bay Area says that he went seeking potential predators on Tinder by using Snapchat's gender-swap filter, and claiming to be a 16-year-old girl. The guy he ensnared turned out to be San Mateo police officer, and that officer was arrested and placed on administrative leave.

The story is, shall we say, problematic. But the catfisher in the case, Ethan — he did not provide a last name in speaking with NBC Bay Area — says he did it with the best intentions. As he explains, he had just learned that a female friend had been sexually assaulted as a child, and he was seeking some sort of revenge by outing another predator out there.

Ethan posed as "Esther," who listed herself as 19 on Tinder (because 18 is the cutoff for the app), and she attracted the attention of 40-year-old Robert Davies, the police officer. His initial message said, "Are you down to have some fun tonight?", and Ethan, as Esther, decided to engage.

It should be noted that initial reports on Davies' arrest, like this one from KPIX/CBS SF, make no mention of the catfishing and suggest that an actual 16-year-old girl was doing the chatting with Davies.

But as the Washington Post has subsequently reported, the story gets more complicated. Ethan moved the conversation from Tinder to the chat app Kik, which is popular with teenagers, and there, as Esther, he told Davies that she was 16. Davies apparently said Esther's age "might be an issue," and when she pressed asking if he was "still down," he replied with a "shrug" emoji and said, "You won’t even send [any] pix of you."

Ethan told Davies that "she" didn't want to share any pics because they might end up on the internet. Davies then allegedly asked to move the conversation to Snapchat, and it's unclear if he then shared explicit photos. The conversation lasted for 12 hours, and clearly Davies should have cut it off the minute he heard the number 16.  

Ethan says he put his phone in Airplane Mode in order to take screenshots of the Snapchat conversation without Davies knowing. After Ethan shared those screenshots, the San Jose Police Department arrested Davies on suspicion of discussing sexual activity with a minor on social media, and he's now been charged with contacting a minor to commit a felony.

The Post calls Ethan's scheme an "extrajudicial sting operation," and Ethan has not indicated he plans to do something like this again. "I was just looking to get someone," he tells NBC Bay Area.