A US soldier was facing a court-martial on Monday on charges that he participated in the execution-style slayings of four Iraqi detainees in 2007. Sgt. Joseph Mayo charged with premeditated murder, conspiracy to commit premeditated murder and obstruction of justice in the incident. According to testimony at previous courts-martial, at least four Iraqis were taken into custody in spring 2007 after a shootout with a patrol. The Iraqis were taken to the US unit’s operating base in Baghdad for questioning and processing, although there was not enough evidence to hold them for attacking the unit.