A motion filed by Sgt. Frank Wuterich's attorneys claims that Gen. James Mattis, who initially leveled charges against Wuterich and seven other Marines, was improperly influenced in legal matters by an aide who was involved in the investigation into the shooting, Col. John Ewers.
According to senior defense counsel Haytham Faraj, court martial law prevents someone involved in the investigation from giving advice on legal matters related to the case.
"The process that we're talking about is essential to bringing charges forward," Faraj told ABC News. "The process has to remain pure to ensure that the accused's rights are protected. We believe it was flawed."
Seven other Marines had been charged in connection to the killings and the ensuing alleged cover-up, but charges against six of them were dismissed and the seventh was acquitted.
"We are waiting for a conviction," said A.J. Kadhim, vice president of the American Iraqi Association of North Texas. "What happened in Haditha was incorrect for everybody. We were so sad to see innocent people get killed for no reason. But we do believe in the court system in the United States. If they are innocent, we will go with the law.
"It's a war zone, you know what I mean?... There's no justice in general," he said.
Mattis, a four-star general who is now commander of the U.S. Joint Forces Command, testified Monday that he had already made his decisions about the charges before Ewers came on as an adviser, reported Bob Lawrence of ABC San Diego affiliate KGTV.
When asked by prosecutors if he was ever influenced by anyone in the case, Mattis replied, "No, never."
The hearing will not determine whether or not Wuterich should be criminally prosecuted for the incident in Haditha, but whether the charges were brought against him properly. If the motion succeeds and the judge drops the charges "without prejudice," then the government can start the process over with new charges.
On Nov. 20, 2005, the bodies of 24 Iraqi civilians were wrapped in colorful cloth and lain on the floor of a building in Haditha, Iraq. Some of the bundles were much smaller than others. Those were the children.
The day before, a squad of U.S. Marines had been attacked by a roadside bomb. One Marine was killed in the attack.
The Marines' squad leader, Staff Sgt. Wuterich, and another Marine then fired at a group of nearby Iraqis who were fleeing the scene. They killed five, according to the account Wuterich gave CBS' 60 Minutes in August 2008.
Wuterich said his men came under fire, but didn't know from which direction the shots were coming. Wuterich ordered his men to clear a nearby house and, by his own account, to shoot first and ask questions later, according to the CBS report. His men cracked the door and rolled a grenade in.
"…I remember there may have been women in there, may have been children in there," he said. "My responsibility as a squad leader is to make sure that none of the rest of my guys died ... and at that point we were still on the assault, so no, I don't believe [I should have stopped the attack]."