SPOKANE, Washington—Ozzie Knezovich seems to revel in pissing people off. “The fact that the extreme left and extreme right hate my guts, I’m good with that,” he told The Daily Beast. “Because I don’t much like them either.” As sheriff of Spokane County in eastern Washington for the past 15 years, Knezovich certainly knows about extremism. He oversees law enforcement in the heart of militia country, just a short drive over the Idaho border from...