After Her by Joyce Maynard

I have been reading this author for years and years and always look forward to her new books. This one especially interested me when I read about it since it takes place in the area in Marin County around Mt. Tamalpais.  I've been there numerous times and have hiked those trails. It's a beautiful place.
The book is a fictionalized account of some murders that took place there in the late 70's - a serial killer I was not aware of.  The story is told by two daughters (Rachael and Patty) of the detective who was put to work on the case. Maynard actually met the "real" daughters when they came to her home for a Writers' Workshop. They gave her permission to fictionalize their story.
It's really a coming of age story about these two young girls, their deep love of one another, and their dysfunctional life as the daughters of divorced parents - and a mother who is always locked in her room, quite depressed. The girls are on their own for the most part and are each other's best friends.
Rachael, the older one, believes she has special powers and wants to help her father solve the mystery and find the killer. As more and more killings occur, right in their own "neighborhood," the sisters are brave and believe that they can find the killer.
Rachael is pulled into a popular group of kids at school when it becomes known that her father is the handsome detective on the case. But as his efforts at solving the murders fails, her popularity wanes and she is shunned by the group.
The girls do encounter the murderer finally and I won't spoil the book. I will say that I really enjoyed the story, the writing and the description of a very special bond of sisterhood.