The US military in Iraq has charged two of its soldiers with the murder of three Iraqis between April and June in the Iskandariya area, south of Baghdad.
Some 20 US soldiers already face murder charges in Iraq
Both of the men are accused of premeditated murder and placing weapons beside the bodies of the dead, who were killed in three separate incidents.
Staff Sergeant Michael A Hensley is accused of three murders and Specialist Jorge G Sandoval of one.
Charges were brought after fellow soldiers alerted the authorities.
Both suspects, who are from the Alaskan-based 25th Infantry Division, are now being held in US custody in Kuwait. Spc Sandoval was detained while at home in Texas.
The military statement announcing the charges says they are "merely an accusation of wrongdoing".
"The soldiers are presumed innocent unless and until they are proven guilty beyond a reasonable doubt of any alleged offense," it adds.
Pentagon investigators are already conducting a number of investigations into incidents of alleged unlawful killings by US forces in Iraq.
In the biggest case, six members of one marine battalion are accused of a role in the killing of 24 civilians in the town of Haditha, north-west of Baghdad, in late 2005.