I followed the "Vampire Clan" murder story through the years, mainly because I was the same age as the teens involved in the case and also played roleplaying games like Vampire: The Masquerade. I never believed I was a real vampire or got into actual bloodsucking, cutting or what have you, but still, the case struck close to home.
As a result I can attest that this movie has done a very good job of presenting the facts of the case in reasonable detail, right down to Jennifer Wendorf's red Saturn convertible. The most obvious changes were in the characterization, which someone probably thought would make the story flow better.
Missing was Rod Ferrell's massive mane of black hair, as well as Scott's somewhat less intrusive chin-length cut. They were given standard short haircuts, which kind of detracts from the weirdness of the original case. The characters of Charity Keesee and Dana Cooper should have been played by opposite actors. The actual Dana was overweight, which could have been pulled off more easily by the round-faced Alex Breckenridge. Marina Black looks absolutely nothing like Dana Cooper (who had short, curly hair at the time,) but wouldn't have been a far cry from Charity.
As far as the personalities go, there was no indication that Scott Anderson was a fidgety, shifty, nutball-type character. He had a hellish upbringing but was normally seen as calm and collected and was mostly a good student. Rod's characterization was reasonable, but I saw Charity as a less demonic force than the movie portrayed her as. She was a generally cheery girl who was grossly misled by her love of Rod, and she took the news of the deaths pretty hard. When it came down to it, she was one of the first to break down, and it was in fact Charity that made the call to her mother, not Dana.
I found it a bit ludicrous that they showed the Lake County Sherriff (who of course wasn't actually present at the questioning in Baton Rouge) just letting Heather go after hearing her story. In real life, Heather spent several months in jail waiting on the authorities to make up their minds before they finally decided to clear her of the charges. And Jennifer and Heather had bad blood between them in the interim due to some of Jennifer's comments to the media and Heather's responses. I highly doubt that they embraced like that when they reunited.
There was also a lot more dirt on Heather that never made it to the DVD. She just barely escaped charges, and there is still some question as to how much she actually had to do with the murders. Also, I wonder how long it took for somebody to come by and swipe the pearls she left on her mother's grave.
Another IMDB user had a good point in that they missed out on some interesting plot by not involving Rod's mother Sondra Gibson in the movie. There were aspects of that mother-son relationship that would have gone far to enhance Rod's insane image. They also ignored the entire role-playing issue, but it might have been better that they did. It's not that the game makes people insane, it's that Rod was already insane to begin with, but not everyone understands that.
All in all, though, the movie was well-done, although I think it's been grossly miscategorized. This is a True Crime story, and people looking for a good Horror flick are doubtlessly going to be disappointed. Yet, that's where you'll always find the movie, mainly because it has the word "Vampire" in the title.
