Previously, a witness had said insurgents managed to separate the three-Humvee convoy by opening fire and forcing two of the vehicles to give chase. Those reports now appear to be wrong, said Lt. Col. Michelle Martin-Hing, spokeswoman for the U.S.-led coalition in Iraq.
The two soldiers, believed to have been kidnapped by insurgents before their mutilated bodies were found this week, and a third soldier killed during the attack had been alone with one Humvee to guard a hydraulic bridge at a Euphrates River canal south of Baghdad.
When the attack occurred, others in the unit could not see the vehicle and were checking on their colleagues by radio, Martin-Hing said.
She said why the three-man team was left would be the focus of an investigation into the checkpoint attack. Army protocols are designed to prevent such attacks.
"The investigation is going to look at whether proper procedures were followed," Martin-Hing told The Associated Press.
The soldiers' bodies were recovered Tuesday after an exhaustive search involving some 8,000 American and Iraqi forces near an electrical plant in Youssifiyah, just miles from the attack scene. Youssifiyah is 12 miles south of Baghdad.
The U.S. military said Wednesday that one and possibly both of the soldiers were tortured and beheaded, and their bodies were sent to Dover Air Force Base in Delaware for DNA testing.
In Brownsville, Texas, the family of Army Pfc. Kristian Menchaca said the military told them his body had been identified as one of the two found Tuesday.
Relatives gathered Thursday at his mother's home to comfort her, and some had held out hope that DNA tests would show Menchaca was still missing and not dead.
"They have confirmed that it is Kristian," his aunt, Hermelinda Gomez, told reporters.
In Madras, Ore., an Army National Guard sergeant staying with Pfc. Thomas L. Tucker's family also confirmed the news to his parents, said Kay Fristad, an Oregon National Guard spokeswoman for the family.
"It's been extremely difficult throughout," Fristad said. "There was always a shred of hope there."
Menchaca, 23, and Tucker, 25, disappeared after the insurgent attack in which a third soldier was killed. All were assigned to the 1st Battalion, 502nd Infantry Regiment, 2nd Brigade, 101st Airborne Division from Fort Campbell, Ky.
Few American soldiers have been kidnapped by insurgents in Iraq, due largely to strict military procedures for those on patrol or at checkpoints: Units must travel in groups of no less than three vehicles, and at no time should soldiers in single Humvee be alone.
Al Qaeda in Iraq claimed responsibility for killing the soldiers, and said its new leader had "slaughtered" them, according to a Web statement that could not be authenticated. The claim was made in the name of the Mujahedeen Shura Council, an umbrella organization of five insurgent groups.
The language suggested both soldiers were beheaded, a claim a U.S. military official in Washington confirmed to the Associated Press. The official asked not to be identified because the final report on the bodies had not been released.