Baghdad ? A weeping Army soldier said Saturday at his murder trial that he can’t remember firing the gun that killed an Iraqi civilian who had stumbled upon the hiding place where he and five other snipers were sleeping.

Sgt. Evan Vela and several of his fellow snipers described the confused scene and their own exhaustion in the May shooting. Tears rolled down Vela’s cheeks as he said in a hushed voice that he could not recall the exact moment he killed Genei Nasir al-Janabi.

“I don’t remember pulling the trigger. I don’t remember the sound of the shot,” Vela said. “It took me a few seconds to realize that the shot came from my pistol.”

The defense rested Saturday in the court-martial at Camp Victory in Baghdad. Vela is charged with murdering the civilian and planting an AK-47 automatic rifle on his body to make him look like an insurgent.

Vela and the other snipers testified that they were confused and exhausted after more than two days of trekking through rough terrain near Iskandariyah, a mostly Sunni Arab city 30 miles south of Baghdad.

They waded all night through swamps and canals, enduring such high temperatures that they were giving each other IVs to remain hydrated, they recounted. They had slept less than five hours in a 72-hour period.

On the morning of May 11, the six Army soldiers had gone to sleep inside their “hide” – a place where snipers can set up and observe targets without being seen. Then al-Janabi surprised them, they said.

After al-Janabi’s son had come looking for his father and was then released by the snipers, Vela said, he heard the order to “shoot” given by Sgt. Michael A. Hensley.

Hensley, who was a staff sergeant at the time of the killing but was later demoted to sergeant, testified Friday that he ordered the man to lie on the ground and was searching him when he saw “military-aged men” who he thought were carrying weapons about 100 yards away.

Al-Janabi began yelling, Hensley said, and he ordered Vela to kill the man. That was the only way to ensure the safety of his men in hostile territory, Hensley testified.

Some soldiers corroborated the accounts of Vela and Hensley; others presented scenarios that did not match. Jorge G. Sandoval Jr., who was a specialist at the time but had his rank reduced to private as part of his sentencing, said he saw no military-age men nearby, which contrasted with what Hensley recounted.

James Culp, Vela’s attorney, called two medical experts Saturday to support his claim that Vela was so sleep deprived that he acted automatically after hearing an order to shoot from his commanding officer. They said he later lied about the events in part because he suffers from post-traumatic stress disorder.

Vela testified that after he shot al-Janabi, he tried to shoot him again because “he was convulsing on the ground and I thought he might be suffering.”

“I just didn’t want him to suffer. It was something I’ve never seen and I got a bit scared,” Vela said.