I can't recall the title of course or the year but it was fairly recent: one woman lived down the shore running some place on the boardwalk and I believe the other was a writer and had married, both had changed their names after they did their time for the murder of another child when they were both children. I remember this was fiction loosely based on a couple of famous real cases about children killing other children and how they grow up and become adults and I believe it was inspired by one girl in particular ( featured in the movie Heavenly Creatures, who grew up to become a mystery writer ), but that's all I remember about that. Anyway the book was a well written, decent mystery/thriller/psychological etc., interesting and a satisfying conclusion with a murderer on the loose who may also be after the women etc. etc. so if anyone remembers what it is, thanks!!