Internet, mostly. There are a lot of True Crime addicts who dig up photographs, interviews, evidence catalogues, etc. and post them on their blogs or wherever else. It's kinda like a real life mystery story where you find the evidence on your own and piece together the story from the details. I try not to go any further than that, although I have visited the hotel where Elisa Lam died and Ted Bundy's apartment when I was in those areas.

The problem with a lot of these true stories, however, is that the "ending" is often underwhelming, same with the ghost hunting adventures. It's only a creepy building, and shadows play tricks on the mind. Elisa Lam was on drugs/had a bipolar episode and climbed into that water tank herself. Ted Bundy was just an asshole.

But they can be good inspiration for fictional crime stories.