Who do you think is the most demented/insane serial killer?
I'd have to say Jeffery Dahmer. He'd go to a gay bar and pick up his date, strangle him to death, have sex with the corpse, masturbate on it later, boil the body to remove the flesh, keep the skull as a trophy, preserve the genitals in a jar, eat the flesh and jerk off to the work-in-progress pictures. If that's not fucking insane, I dunno what is.
Second place would be Eddie Gein, the model for Buffalo Bill and Psycho. Need I say more?
If you need some reference go here:
http://www.crimelibrary.com/serial_kill ... index.html