Actual Killers in Films
First of all, I found The Bedroom not graphically violent, but disturbing & confusing. Maybe it was just the awful English subtitles that I had on my copy.
Again the use of drugs is a recurring element in the films of Sato (Myson in Naked Blood). The drug they use in this film is actually a brand name: Halcion is used for short-term treatment of insomnia.
However the thing that shocked me the most was the fact that Sato had a real-life cannibal killer playing the role of Mr Takano.
Any other examples of actual killers in films?