The Fallen Man by Tony Hillerman (2005, Abridged, Compact Disc)

Human bones lie on a ledge under the top of Shiprock Peak, the remains of a murder victim undisturbed for more than a decade. Three hundred miles across the Navajo reservation, a harmless old canyon guide is felled by a sniper's bullet. Joe Leaphorn, recently retired from the Navajo Tribal Police, believes the shooter and the skeleton are somehow connected and recalls a chilling puzzle he was previously unable to solve. But Acting Lieutenant Jim Chee is too busy to take any interest in a dusty cold case ... until the reborn violence of it hits much too close to home.