A Cold Heart (Alex Delaware #17) by Jonathan Kellerman

LAPD homicide detective Milo Sturgis summons his friend, psychologist-sleuth Alex Delaware, to a trendy gallery where a promising young artist has been brutally garroted on the night of her first major showing. The details of the murder scene immediately suggest to Alex not an impulsive crime of passion, but the meticulous and taunting modus operandi of a serial killer.

Delaware's suspicions are borne out when he and Milo find there's a link between the artist's death and the murder of a noted blues guitarist. The twisting trail leads from halfway houses to palatial mansions, and from a college campus to the last place Alex ever expected: the doorstep of his ex-lover Robin Castagna. As more killings are discovered, unraveling the maddening puzzle assumes a chilling new importance --- stopping a vicious psychopath who's made cold-blood murder his chosen art form.