Jigsaw by Jonathon Kellerman
Psychologist Alex Delaware and his best friend, homicide cop Milo, are working on 2 different cases that Alex thinks might be related. A retired homicide detective that Milo knew from years earlier is found dead in a freezer with her arms cut off. Around the same time, a young woman is found sitting at her kitchen table with her throat slit. Then the daughter of the dead cop goes missing. It's a complicated case with some good twists. And it's always great to see Alex and Milo putting their heads together to find the bad guy.