Trent Thomas was the first of eight service members -- seven Marines and a Navy serviceman -- to go to trial in the killing. He faces a maximum sentence of life in prison.
Witnesses at the trial testified that the squad members abducted the victim from his house in the town of Hamdania and shot him in a ditch. The service members then tried to cover up the killing by planting a gun near the victim.
The case is one of several in which the U.S. military is investigating alleged unlawful killings of civilians by U.S. forces in Iraq.
In the latest case, the U.S. military today said that two soldiers have been charged with the premeditated murder of an Iraqi near the northern city of Kirkuk in June.
The U.S. military said the two soldiers were charged after reports of "alleged wrongdoing made by fellow soldiers."