Newbie chiming in, just to say thanks for all the great recommendations! I love a good documentary, and even though I'm a huge horror fan I'd say documentaries make up 95% of what I watch on Netflix.
Here's a good one I watched recently (and then found out not long after I watched it that one of the main guys involved in this story lives very close to me . . . and judging from his Facebook posts, he's a racist piece of crap). Anyway, check it out, it's quite fascinating:
Finders Keepers (2015) - IMDb