TIKRIT, Iraq – U.S. soldiers stepped outside the law when they murdered three Iraqi detainees "in cold blood," a prosecutor told a U.S. military hearing on Friday.

"U.S. soldiers must follow the laws of war. That’s what makes us better than the terrorists, what sets us apart from the thugs and the hitmen," said Captain Joseph Mackey, closing arguments for the prosecution of the four U.S. servicemen.

"These soldiers did just the opposite. They cut them loose and murdered them in cold blood," he said.

The hearing into the deaths on May 9 during a raid on a suspected insurgent camp on an island in the marshy fringe of Thar Thar Lake, southwest of Tikrit, will determine whether the four soldiers should be court-martialled for the killings.

If found guilty of premeditated murder, they could face the death penalty.

It is one of several probes into suspected abuse by U.S. troops in Iraq, including the alleged killing of 24 unarmed civilians by U.S. Marines in Haditha. On Thursday, six Marines were charged with assault in an incident in Hamdaniya.

The soldiers — Private First Class Corey Clagett, Specialist William Hunsaker, Staff Sergeant Raymond Girouard and Specialist Juston Graber — are from the 101st Airborne Division and were serving in Samarra, north of Baghdad.

They have said the detainees were trying to escape when they were shot, but military prosecutors have said they were freed before being killed.

"For this they are not war heroes, they are war criminals. And justice states that they face trial," Mackey said.

The prosecution presented testimony from another soldier that the men smiled as they fired, and also contested claims the men were urged by their commanding officer, Colonel Michael Steele, to "kill all" of the insurgents during the operation.

The defense argues the four soldiers simply did what they had to do in a dangerous situation.

"They went into a hot LZ (landing zone) with the pre-thoughts that they were going to fight terrorists, fight al Qaeda, insurgents," said Clagett’s lawyer, Paul Bergrin, describing how the assault was launched by helicopter.

"Every single one of them followed their mission and their rules of engagement … There is no physical evidence, there is no forensic evidence, there is no scientific evidence whatsoever," he said. "They are victims in this case and they deserve to be treated as victims, not as criminals."

The defendants have been charged with premeditated murder, attempted murder, conspiracy, communicating a threat, and obstructing justice, the latter two charges for threatening to kill another soldier if he informed on them.

© 2006 Reuters