Rattlesnake Crossing by J.A. Jance

When Clyde Philips, a local gun dealer, dies violently, his stock of high-powered assault weapons vanishes, and two sniper slayings follow soon after, suspicion falls upon Alton Hosfield, an embittered rancher at odds with the federal government, the environmentalists, and anyone else he sees as a threat to his isolation. Sheriff Brady, however, suspects that the solution may lie elsewhere, and her investigation takes her into the bizarre practices of a local resort whose appeal is equal parts New Age spiritualism, Native American pantheism, and cold-blooded materialism.