Truth may be stranger than fiction, but in the case of this documentary, it's an improvement. Serial killers have been a compelling subject for dramatization since Hitchcock's "Psycho," at least in American popular culture. But the fascination dates back to Jack the Ripper, and even farther back to the Middle Ages. This year it's Netflix's recent portrayal of the "good nurse" killer, a dismal excuse for biographical adaptation. It might have been worthwhile if it had offered new insight into horrible events, portrayed compelling emotions, or delved into human nature. The result could have been interesting, even entertaining, like a thriller. This documentary accomplishes all of this with no convoluted plot and contrived performances. The actual killer, Charles Cullen, is a far more chilling and impenetrable human being than the one portrayed by Eddie Redmayne. Cullen's matter-of-fact delivery as he explains the motivations that lead him to kill patients and his almost childlike self-possession are unnerving. Redmayne is a good actor, but his choice of intonation and nearly comatose performance failed to capture these real qualities. With straight-forward story telling and genuine emotion, this film imparts unimaginable horrors all the more frightening because they are so credible.

It's difficult to tell just how accurate this documentary is. I take it that it's pretty accurate, since the original people were involved and most did not try to hide their shame at being unwittingly involved with this man's murders.

What's missing though is more in-depth information about his childhood, his psychological motivations, or other things that makes criminal pathology a fascinating field. His motivation is so meagerly discussed it's almost non-existent. Anyone trying to get into the mind of the killer will be disappointed here.

What I am most shocked at is that criminal investigations were not brought against the hospitals and administrators that suspected (ie knew) this was going on and just passed him on to other hospitals. They would seem as responsible for those deaths as the murderer, yet not a one of them has been brought to trail? That is so unthinkable that it galls.

All in all a reasonable documentary, but it leaves quite a bit out that would have made the rather slow-moving commentary more interesting and informative. We know the story, but little about the "why" (other than the killer was seriously warped, of course). The fact that his murders were at times random was an indication there was far more going on here than basic mercy killings. The documentary would have done well to delve deeper into the psychology and motivation of that part of this story.

I watched this having watched the film in which Eddie Redmayne started as Charles Cullen.

I'm glad I did it this way round, so many things I found hard to believe in the film, were actually true, the film wasn't sensationalised, it seemed to stick quite rigidly to the content.

What a documentary should be, thought provoking, dramatic, revealing, and a little bit shocking, some parts of it were actually hard to fathom, that is one messed up system.

Amy Loughren's thoughts were astonishing the whole way through, once again, I'm speechless at how rotten the establishment was, how many lives could have been saved.

One thing the film didn't really get into was Cullen's motivation, you will actually hear that in his own words here, the interview sequences were astonishing I thought. What a curious guy, I'd like to see more on him, to try and understand him a little better, he's impossible to piece together.

8/10.