prosecutors are describing this plot as chilling. that's because they say he wanted to kill as many people as possible on d.c.'s metro system. authorities searched the virginia home of the computer engineer after his arrest on wednesday. the criminal complaint says the 34-year-old naturalized u.s. citizen who was born in pakistan scouted several locations in the subway system in northern virginia near the pentagon. the complaint also says ahmed told f.b.i. agents posing as al-qaida operatives he wanted to kill military personnel and he figured out a way to do it by putting explosives in rolling suitcases atush hour on the metro. prosecutors say he videotaped metro stations and in april, he started turning over the videos, the sketches and the photographs as he met with these f.b.i. agents. he appeared in court on wednesday. we don't have a sketch or picture of him. he remains in custody facing a three count indictment. authorities say metro passengers were never in danger. but it's not clear what led the