RIVERSIDE, Calif. (AP) — For the second time in two weeks, a Marine accused of killing an unarmed detainee in Fallujah, Iraq, was jailed for refusing to testify about a former squadmate.

Sgt. Jermaine A. Nelson was jailed on Tuesday for contempt of court and could be held for up to 18 months.

Nelson is among three Marines accused of shooting unarmed captives in November 2004 during some of the heaviest fighting of the war. The Marine clasped his hands behind his back before marshals led him away.

"There are few things that give me less pleasure," U.S. District Judge Stephen Larson said. "I have a profound respect for his service to our country. ... Everyone in this courtroom is indebted to him."