The key witness in the government's trial of 14 alleged white supremacists told a federal court jury in Fort Smith, Ark., about the slaying of a pawnshop owner and an aborted plan to assassinate an FBI agent. James Ellison, the former leader of the Covenant, the Sword and the Arm of the Lord, a religious-military group that was based in north Arkansas, testified that Richard W. Snell told him he had killed a pawnshop owner in Texarkana during a robbery. Ellison said the planned assassination of FBI agent Jack Knox of Arkansas was aborted because of a traffic accident. Ellison is serving a federal prison sentence for racketeering and weapons law violations when he led the organization. He is considered an unindicted co-conspirator in the case. It was Ellison's second day of testimony in the trial of 14 men accused of seditious conspiracy and plotting to kill Knox and U.S. District Judge Franklin Waters of Arkansas.