A U.S. Army sergeant accused of masterminding a plan to kill Afghan civilians for sport appeared before a military hearing Tuesday in the state of Washington.Officers will decide after the two-day hearing if there is enough evidence to send the case against Staff Sergeant Calvin Gibbs to a court martial.Gibbs is the highest-ranking of five soldiers charged with murdering three Afghan civilians in separate incidents while on patrol in Kandahar Province earlier this year.He is also accused of threatening fellow soldiers in an attempt to cover up the crimes.If convicted, Gibbs could face the death penalty. He has denied all charges.Another seven soldiers from the same unit are accused of various crimes related to the case, including conspiracy to cover up the slayings and the use of illegal drugs.The soldiers say Gibbs devised scenarios under which he could kill Afghans and pressured the soldiers to participate in the killings.U.S. army officials have condemned the murders, saying they undermine military efforts in Afghanistan – Voanews