Newly unsealed court documents show the Columbus man charged with plotting a U.S. attack after receiving overseas training pleaded guilty to multiple charges nearly two years ago. Abdirahman Sheik Mohamud pleaded guilty in August 2015. Federal prosecutors say Mohamud received training in 2014 in Syria, and then returned to the U.S. with a plan to kill military officers or others in uniform. They say he also researched places to carry out attacks. Mohamud's attorney declined comment on why it took two years to reveal the guilty pleas.