Listening Woman by Tony Hillerman

The blind shaman called Listening Woman speaks of witches and restless spirits, of supernatural evil unleashed. But Lieutenant Joe Leaphorn of the Navajo Tribal Police is sure the monster who savagely slaughtered an old man and a teenage girl was human. The solution to a horrific crime is buried somewhere in a dead man's secrets and in the shocking events of a hundred years past. To ignore the warnings of a venerable seer, however, might be reckless foolishness when Leaphorn's investigation leads him farther away from the comprehensible . . . and closer to the most brutally violent confrontation of his career.