Serpentine by Jonathon kellerman

 Serpentine is the latest in the long-running Alex Delaware/Milo Sturgis series. Cop Milo is assigned a cold case involving a death that happened in the 80s that was assumed to be a car accident at the time, but which is now thought to possibly have been a homicide. The daughter of the woman who died in the car is trying to find out more about her mother's death. Milo and his friend (psychologist) Alex think the chances of finding anything new after all this time are slim to none but they give it their best effort--and discover that the original victim might not be the only death they're investigating.

It's a good story and I like the rapport between Alex and Milo.