they decided to squeeze steven hatfill. it started with what the fbi calls "bumper lock"-- 24-hour surveillance-- and they let him know they were doing it. >> management was convinced he was the right guy. and so, as a result, there were intense surveillance-- bumper- lock type surveiance-- of dr. hatfill that went on for months. >> there is a brutal, sustained attempt by the fbi in these cases to turn or crack the suspect, and it doesn't look much like what happens on tv. it can be quite rough. and what they were doing to hatfill clearly was an effort to create pressure in the hope that he would crack. >> narrator: another playbook tactic is search and seizure. hatfill's apartment was taken apart. >> when they showed up for the raid, they brought the press. they brought the press en masse. they had them all over the place with their trucks, with their helicopters. >> he returns to his home to find a full-blown media circus-- helicopters swooping in the air, all kinds of camera crews around as his place is kind of being ran