Hunter, the chairman of the House Armed Services Committee, said Tuesday that the slayings represented a tragedy for the U.S. military, the North County Times reported.

"I'm concerned that the 922,000 who have served honorably in Iraq will be tarnished by the actions of what one squad did on one day," Hunter, R-El Cajon, told the Times.

Hunter's committee and its Senate counterpart are getting ready to hold hearings on the slayings in June.

The primary focus of a probe being conducted by the Naval Criminal Investigative Service is on a dozen members of Kilo Company, an element of the 3rd Battalion, 1st Marine Regiment, 1st Marine Division, the Times reported.

On Nov. 19, at least 24 Iraqi civilians in the city of Haditha were killed shortly after Marine Cpl. Miguel Terrazas of Kilo Company lost his life in a roadside bomb explosion.

Members of Congress, as well as family members of some Kilo Company Marines, have said some Marines went on a rampage after Terrazas' death, shooting noncombatant Iraqis, including women, children and elderly men.

Members of another Pendleton unit from the 3rd Battalion, 5th Marine Regiment, 1st Marine Division, also are under investigation for the alleged killing of an Iraqi west of Baghdad in late April.