the person behind the attacks remained unknown until june 17, 2011 when yonathan melaku was arrested. he is a 22 year old naturalized ethiopian immigrant and marine corps reserve lance corporal. he was found at arlington national cemetery while it was closed. he was carrying spent shell casings, a notebook containing references to the taliban and osama bin laden, and plastic bags filled with ammonium nitrate, a common component of homemade explosives. he also left his car parked in the woods near the pentagon, police said. he had also been recently charged with breaking into 27 cars in suburban washington. the investigation of the incident connected melaku to the shootings. on june 23, 2011, he was charged with two counts of willfully injuring the property of the united states. if he is convicted of those charges, he could go to prison for 20 years. melaku is also charged with two counts of using a firearm during a violent crime. if he is convicted of those charges, he could go to prison for the rest of his life. more charges are possible.