The goodbye man / Jeffery Deaver.

"In the wilderness of Washington State, expert tracker Colter Shaw has located two young men accused of a terrible hate crime. But when his pursuit takes a shocking and tragic turn, Shaw becomes desperate to discover what went so horribly wrong and if he is to blame. Shaw's search for answers leads him to a shadowy organization that bills itself as a grief support group. But is it truly it a community that consoles the bereaved? Or a dangerous cult with a growing body count? Undercover, Shaw joins the mysterious group, risking everything despite the fact that no reward is on offer. He soon finds that some people will stop at nothing to keep their secrets hidden . . . and to make sure that he or those close to him say "goodbye" forever"--