True Story?

I saw this movie and was a bit disturbed by it.
as others have said (in another post) the testicle scene is just too much

anyways, i did a web search to see in fact if this is based on a true story, and couldnt dig anything up - anyone know the real story? Obviously, i am certain the filmakers embelished on the real story, but i was just wondering if this truly did come from a real story.