CLAYTON, Mich. — David B. Stone Sr. and his wife, Tina, made no secret about the fact that they were part of a militia, neighbors say. The couple frequently let visitors in military fatigues erect tents in front of their trailer home at the intersection of rural dirt roads, and the sound of gunfire was routine.

“In Michigan, I don’t think it’s that big of a deal to be in a militia,” said Tom McDormett, a neighbor.

He added: “They would practice shooting, but that’s not a big deal. People do that all the time out here.”

But last Saturday night, Mr. McDormett watched through binoculars as the police raided the Stones’ home, tearing off plywood from the base of their two connected single-wide trailers to search under the floors. By Monday, the Stones were in green prison garb in a federal courthouse in Detroit, two of nine defendants facing sedition and weapons charges in connection with what Attorney General Eric H. Holder Jr. called an “insidious plan.”