Was this explained in the film??
So we find out Carrie Ann died when she was little, but how did no one know about that? Wouldn't they have had funeral services with the family and all the neighbors at the time would have known she died as a kid?
Ryan wasn't exactly hiding, everyone knew he was there and who he was, so wouldn't this have solved everything from the beginning? If it was known Carrie Ann died and they had another kid who murdered the parents isn't it fairly obvious that it's him?
To me that was a major loop hole in the story but maybe I missed when this was explained.