Books like J. D. Robb - In Death Series : Books 25-26 by Nora Roberts

Investigating the brutal murders of two vacationing families in sunny Virginia Beach, FBI agents Ryan Sinclair and Buzz Crane suspect the work of a notorious serial killer and tap the skills of preeminent clinical expert Charlotte Stone, who is also the culprit's only known survivor.

"I very much need to be dead." These are the chilling last words left by a man who had everything to live for but took his own life. In the void that remains stands his widow, FBI agent Jane Hawk, surrounded by questions destined to go unanswered unless she does what all the grief and fury inside her demand: Find the truth, no matter what. People of talent and accomplishment, people seemingly happy and sound of mind, have recently been committing suicide in surprising numbers. A disturbing pattern is beginning to emerge. Jane is determined to give up everything to find out why. And if that means going rogue and becoming America's Most Wanted, then so be it. Those arrayed against her are legion, and devoted to protecting something profoundly important-or terrifying-enough to exterminate any and all in their way. But Jane is as clever as these enemies are cold-blooded, as relentless as they are ruthless. And she is driven by a righteous rage they can never comprehend. Because it is born of love.

LAPD detective Hieronymous (aka Harry) Bosch is a loner and a nighthawk. Called out on a routine drug overdose case, Bosch soon realises that the victim found lying in the Mullholland Dam drainpipe is no accident case. Billy Meadows was a fellow 'tunnel rat' in Vietnam and Harry swears to bring the killer to justice.