Thanks for the link. That is a pretty similar reading of the situation. Though, I don't really agree with the idea that Lyla was befriended by Olive and moved in (Olive doesn't have a memory saying that Lyla moved in, for one), though that could be another interesting way of interpreting it. It could be another of Olive's tricks.

I like to think of the cemetery as a cover for Olive's operation. If she killed people, would she really put them all right there on display? She throws people (like the police) off by hiding everything in plain view, maybe.

I'm sure that other people have come up with other good explanations for Olive's little collection of deaths and types of ghosts. She could have been unwillingly connected to death in another way, or have some sort of terrible curse surrounding her. I just think that a conscious effort to collect victims makes more sense for someone who has devoted her life to seeking knowledge.