A Marine was charged Tuesday with murder and dereliction of duty for his alleged role three years ago in the death of detainee in Fallujah, Iraq.

Sgt. Ryan Weemer is the third person charged in the case that centers on allegations that a Marine squad shot a group of unarmed captives during heavy fighting in November 2004.

The case came to light when Weemer, 25, applied for a job with the Secret Service. Investigators claim Weemer described the killing during a polygraph test that included a question about whether he had participated in a wrongful death.

Weemer was in the Marine Corps' Individual Ready Reserve, meaning he had completed his active duty, until the Marine Corps reactivated him this week, said Lt. Col. Sean Gibson, a Marine spokesman. The move allows the military to court-martial Weemer.

Weemer, of Hindsboro, Ill., has been assigned to Headquarters Battalion, 1st Marine Division, while he awaits trial at Camp Pendleton. He was not being held in the brig.

Weemer's attorney, Paul Hackett, reached by telephone, said he had not been notified that Weemer had been charged. He declined immediate comment.

The battle of Fallujah was the second time that year Marines tried to take the city. The first fight in April 2004 came after the killing and mutilation of four Blackwater private security contractors, whose bodies were strung from a bridge.

Ground forces entered Fallujah and faced some of the heaviest fighting seen at that point in the war, often engaging in hand-to-hand combat.

The killings on Nov. 9, 2004, came after troops captured men they believed had been shooting at them from a house. Weemer was a rifleman in a four-man fire team.

At the time, Weemer was a corporal. Weemer was promoted to sergeant in April 2006 as a reservist before he came under investigation, Gibson said.

Also facing court-martial is Sgt. Jermaine A. Nelson, who was charged with murder and dereliction of duty, and squad leader Jose Nazario Jr., who was charged with one count of voluntary manslaughter in the killing of two captives. Because he completed his military service, the former sergeant faces charges in federal court.