The True Story This Was Based On....SPOILERS
This was based on a true story and many of the events in the movie (cooking body parts, feeding body parts to the dog, freezing a body, motive) were remarkably on point. I thought what an awful mashup of the movie, but as they say truth is stranger than fiction.
Gary Heidnik: To Hell and Back
http://www.trutv.com/library/crime/serial_killers/weird/heidnik/index_1.html