RIVERSIDE -- A second Marine has been found in contempt of court for refusing to testify before a federal grand jury and has been ordered to jail.

Sgt. Ryan G. Weemer, charged with murder in the death of an Iraqi detainee in Fallujah in 2004, appeared in uniform before U.S. District Court Judge Stephen Larson on Thursday and was ordered into custody after a brief hearing Thursday.

Weemer can be held for up to 18 months unless he decides to testify before the grand jury.

The jury is investigating Weemer's former squad leader, Jose Nazario, who is no longer in the Marine Corps. Nazario is charged with voluntary manslaughter in the killing of two Iraqi captives during fighting in Fallujah in November 2004. He has pleaded not guilty.

Last month, a third defendant in the case, Sgt. Jermaine Nelson, spent a week in jail when he refused to answer the grand jury's questions. A judge freed him after he agreed to appear before the panel next week and at least hear the questions that jurors may ask.

Like Weemer, Nelson is charged with one count of unpremeditated murder. Investigative hearings for the two Marines to decide whether their charges will stand will take place at Camp Pendleton later this year.