But the findings called into question the way the military handled the aftermath of the shootings.

For example, a key assertion of the news release issued by the military on the day of the killings was that “a weapon was recovered from the wreckage.” But the military said Sunday that no one claimed to have found a weapon in the car or had seen a weapon taken from it.

Instead, one of the soldiers at the scene reported seeing an Iraqi police officer pull something from the burned car and then place it in the front seat of an ambulance, according to Lt. Col. Steve Stover, a spokesman for the Fourth Infantry Division, which patrols Baghdad.

The soldier never said the item pulled from the car was a weapon, he said. But the soldier’s account nevertheless formed the basis for a statement in an initial internal military assessment of the attack, which said that a weapon had been pulled from the car.

“We don’t believe there was any cover-up,” Colonel Stover said.

The investigation also revealed that the car had already passed through a major checkpoint leading into the airport, which required the occupants to submit to a thorough search for weapons and other dangerous objects. As they had many times before, the bank employees then drove down the main civilian road to the airport.

But this time they encountered a four-vehicle military convoy that was not supposed to be there. The convoy had taken the wrong road and failed to turn into a military checkpoint. Instead, the military vehicles had traveled down a road that serves as the main entry for thousands of Iraqis who drive to the Baghdad airport.