CAMP PENDLETON, Calif. (AP) — It has been more than four years since Staff Sgt. Frank Wuterich's squad of Marines was accusing of killing 24 Iraqis, some unarmed women and children. It has been more than two years since he was court-martialed.

As the November 2005 killings have faded in many minds, the only remaining and highest-profile defendant in the biggest criminal case against U.S. troops to arise from the Iraq war faces a key test Friday.

A military judge is scheduled to rule whether to dismiss charges against the former squad leader. Wuterich's attorneys argue that unlawful command influence occurred while a general was considering a court-martial and should prevent the case from going to trial Sept. 13.

If the judge agrees, it would mark a stinging finale for the military. Eight Marines were charged in December 2006 with murder or failure to investigate the killings. Six have had charges dropped or dismissed, and one was acquitted.

Wuterich, 30, faces reduced charges of voluntary manslaughter, aggravated assault, reckless endangerment, dereliction of duty and obstruction of justice. He is currently assigned to administrative work at 1st Marine Division headquarters at Camp Pendleton.

The deaths occurred after a Marine was killed by a roadside bomb in the town of Haditha.

Wuterich and a squad member were accused of shooting five men by a car at the scene. Investigators say Wuterich then ordered his men to clear several houses with grenades and gunfire.

A full investigation didn't begin until a Time magazine reporter inquired about the deaths in January 2006, two months later.

At his preliminary hearing, Wuterich said he regretted the loss of civilian lives but believed he was operating within military combat rules when he ordered his men to attack.

At issue in Friday's anticipated ruling by Lt. Col. David Jones is whether commanders acted improperly or can be perceived to have acted improperly before Wuterich was court-martialed in December 2007. Defense lawyers allege the commanders were improperly influenced by an aide who had investigated the case.

The judge said Wuterich's attorneys presented credible evidence regarding the role of military lawyer, Col. John Ewers, who investigated the Haditha killings and later became a top aide to the generals who brought charges against Wuterich and ordered him to stand trial.

Gen. James Mattis, who brought charges, acknowledged during testimony that Ewers was in the room when allegations of wartime abuse were discussed but denies ever getting advice from him on the Haditha case.

The defense argues that Ewers' mere presence stifled junior attorneys who were assigned to advise the general. Court papers describe how Ewers, who was seriously wounded in Iraq in 2003, had a stellar reputation and a long history with Gen. Mattis.

That same argument worked for another defendant.

In 2008, a judge dismissed a case against Lt. Col. Jeffrey Chessani, who was charged with dereliction of duty for failing to investigate the Haditha deaths.

Copyright 2010 The Associated Press.