[SERIOUS] What was the most creepy incident where your gut-instinct turned out to be completely correct?

I used to play a bar trivia game fairly often, and there would be yearly gatherings and stuff like that with usually dozens to a couple hundred regional people going to the same place, mostly to get drunk and just have fun without really caring about the actual games. All the scores were televised to other players so you got to recognize other players/teams pretty quickly. Anyway

A few years ago a guy came from a couple hours away to visit our town and just meet some of the people around here. A friend and I both got the exact, "this dude is weird" impression right away. Not in the way I'm weird in that I've been doing stuff like pub quizzes in bars since I was 16, but the guy just didn't seem right. Just about everyone else thought he was nice, just quiet. Then a few months after that, we went to one of those big gatherings, easily over a hundred people basically going to the same bar in a town to drink and have a good time and the dude went up to that, and was being just weird again. Not everyone got the vibe still, but I definitely did.

So fast forward a few months not really thinking about it or having to see him again and we hear the FBI raided his house. Turns out the dude had a tooonnnnn of child porn and was distributing gigabytes of it online. Dude was major major pedo. He got in even more legal trouble after that too, made national news for creeping on high school football recruits at a major college - not gonna post links (don't know rules and all), but easy to google I imagine.

tl;dr - met a creepy dude, thought he was really weird even though lots of people just thought he was nice and quiet, he was super into kiddy porn and got raided by the FBI. x_x

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