I recently spent hours online looking for the one film that scared the he11 out of me worse than any other, back in the mid to late 90s and I could never find it! I went through tonsss of online serial killers hell looking for him, I remember what he looked like, a disgusting backwood hillbilly creep and he had a sidekick buddy, and it was a documentary film of re enactments and real footage on a VHS rental.
It was the one and only time, I ever ever felt physically shaken and went all through my house at 2 in the morning, closing any and all blinds, windows, curtains, door locks, that one really put me on the edge, I just cannot remember who it was!