Stag : a novel / Dane Bahr.

Enhanced descriptions from Syndetics:

It's 1989 and Amos Fielding, onetime sheriff of Oscar, Iowa, is in his early seventies and grieving the recent loss of his wife, Sara. He packs up his few belongings and heads to a ranch in the far northwest corner of Washington State.The farther he can get from Oscar and his years there as sheriff, the better. Eager to escape painful memories, Fielding throws himself into the daily chores of a gentleman rancher. But there is evil afoot, as dark as any he faced in Oscar. A cold-blooded, amoral psychopath has been stalking troubled young women in the surrounding woods, staging elaborate scenes of his crimes. The local chief of police has turned a blind eye to the cases. In fact, the only law enforcement agents genuinely concerned about justice are Dee Batey (a recovering alcoholic and former detective turned wildlife officer) and Philip Wilson (an overly ambitious and weirdly obsessed young Seattle FBI agent). It is Batey and Fielding's growing friendship that provides the lure that will pull Fielding back into the world he so desperately wants to escape as the three team up to hunt a killer and stop the predator from finding new prey.