Search - Nightmare in Napa

I just finished reading this book and it was very good. I was surprised at the ending who the killer was and why. Halloween night in idyllic Napa, California: a transplanted Southern beauty queen and a popular engineering graduate from the Napa area are brutally stabbed by an intruder who entered their home through a first floor window. A third roommate heard the horrific commotion, but never saw the killer. News of the tragedy sent shock waves throughout the peaceful region as well as the nation--but while investigators pursued every angle from a satanic cult to a disgruntled suitor, the murders of Leslie Mazzara and Adrianne Insogna remained unsolved. Until someone came forward with a shocking confession--someone who was close enough to the women to escape suspicion. Someone who knew the victims all too well.