Before the jury broke to determine his sentence, Vela apologised to the court, the army and to one of the sons the man he shot.

"When I came to Iraq, I didn't come to do anything wrong," Vela told the jury, reading from a handwritten statement.

"I failed my standards, your standards and the standards of the army. All I can say is I'm sorry and ask for mercy."

Ordered to shoot

After al-Janabi accidentally discovered their hiding place, Vela's commanding officer ordered him to shoot the man.

"I failed my standards, your standards and the standards of the army. All I can say is I'm sorry and ask for mercy" Sergeant Evan Vela

The soldiers said he was making noise and they feared he was trying to attract the attention of a group of men nearby.

An AK-47 was then planted on the dead man's body.

Mustafa al- Janabi, the murdered man's son, gave evidence at the trial.

"I know this criminal has a family, a wife and children," he said.

"Just like they will miss him, we also miss our father. So I hope you will consider that and please not forget about us."

Vela and several of his fellow army snipers took the stand during the trial, describing their confusion and exhaustion after more than two days of trekking in high temperatures.

Other members of Vela's unit were earlier charged either in al-Janabi's murder or other killings that occurred around the same time.

Planting evidence

In September, a military panel acquitted Spc. Jorge G. Sandoval, Jr on charges he killed two unarmed Iraqis in April and May, but it convicted him of planting evidence on one of the men in an attempt to justify the actions.

In November, Sgt. Michael A. Hensley was acquitted of murder charges in the three deaths, but was convicted of planting evidence by placing a rifle with al-Janabi's body.

Hensley and other members of the sniper unit said that after they were accused of the crimes, they were ignored by their chain of command.

"I think they pretty much abandoned all three of us," Hensley said after he had testified in Vela's case.

"These guys [Vela and Sandoval] were the golden children of the battalion, they could do no wrong, even after these close kills."