Manson
Laurence Merrick and Robert Hendrickson's 1973 documentary is a chilling account of the Manson murders. It gives a insight to "The Family" that's every bit as creepy as a horror film. One of the most fascinating documentaries I've seen. This is most definitive chronicle of Manson you'll get. Essential!
http://www.imdb.com/title/tt0068918/
http://www.youtube.com/watch?v=jm9cjrwBIdM