How did they suddenly know at the end that Diondra killed the one sister? They got the Angel of Debt to confess to the other two deaths, but he wouldn't have known what was happening in the bedroom. The only two people who knew Diondra killed the sister was Ben and Diondra, and neither one of them were talking.
Another question. When Libby visits Diondra and sees her daughter, she suddenly becomes upset and hides in the bathroom. Why?
shareI don't recall all the specifics, but I remember the daughter barging in and finding Libby with The Necklace, and knew the jig was up. Actually, IIRC, she ran up there as she figured Libby *would* find it - even more far-fetched that the daughter knew of its significance. (The bathroom is an odd place to keep jewelry, but they had to "get" Libby into the same room with it; so that was awkward.) This Revelation-via-Jewelry plot device often annoys me, unless it's set up beforehand so that it makes sense. Because really, how many women have just one specific necklace - for example - that they wear all the
time, and how many kids pay that much attention
to such things, anyway? I dunno, maybe I'm
forgetting its importance to the story, or it's just
that I was such a tomboy that I didn't have the usual (?) interest in jewelry of most girls.
At the end, the brother is released on his appeal, so you have to assume (although this certainly wasn't shown) that the brother ended up ratting out Diondra as the real killer. Definitely no way for Charlize to know unless Ben told her.
shareI haven't read the book or seen the movie in a minute but i think the daughter mentioned something that only she would know if she took the girls diary. So I think it started to click for Charlize's character.
shareWell, there was a necklace that might have had something to do with it. Diondra took a necklace off of Mom the night of the murders (I think - it was kind of hard to tell who was who) and the film showed Libby had something in her hand after her escape from Diondra.
shareIn the book, there's DNA on Michelle's sheets that matched Diondra. Or maybe they still had the DNA from under Michelle's fingernails. Don't remember the specifics, but I know Diondra was arrested because of the DNA evidence.
in the book Libby's a clepto (something that's apparently not in the movie at all) and steals a lipstick from the bathroom, and this is later used to match Diondra's DNA to the blood on the bedsheet or maybe to Michelle's bedclothes or whatever.
MariaDeluca is right about the reveal in the book but i think the movie covers it differently.