>> sir, is steven hatfill still a suspect in the anthrax case? >> mr. hatfill is a person of interest to the department of justice, and we continue the investigation. and for me to comment further would be inappropriate. >> this was really an extraordinary moment. their lips may have been saying, "we will not confirm that dr. hatfill is under investigation," but their body language was saying, "look, here. this is the guy." >> narrator: but steven hatfill did not do what the justice department and the fbi intended- - break under the pressure. instead, he went on the offensive. >> hatfill doesn't fold. on the contrary, the very sort of gregarious, energetic core of hatfill becomes filled with rage. "how dare they take me on?" >> i want to look my fellow americans directly in the eye and declare to them, i am not the anthrax killer. i know nothing about the anthrax attacks. i had absolutely nothing to do with this terrible crime! >> we were surprised. we weren't expecting him to do that. we didn't think it was at a point where he was going to go public wit

but the federal investigation does focus on a former usamriid scientist named steven hatfill.had worked here in the late '90s. investigators say eight people flagged hatfill to the fbi. >> i want to look my fellow americans directly in the eye and declare to them, i am not the anthrax killer. >> on his resume, hatfill claims a working knowledge of america's former biological weapons programs. the fbi says a witness reports hatfill claimed to have prepared and used anthrax as a weapon in the late 1970s while studying in southern africa. >> i have never, ever worked with anthrax in my life. >> the suspicion is fueled by hatfill's job at saic, a government contractor. he works on biological weapons defense. one project hatfill proposed about risk of anthrax sent through the mail is proposed a single letter being sent to government agencies and news agencies. >> that was very interesting to us in that it is what happened. almost prescient. >> hatfill says it's all for training first responders, doctors and army medics on how to handle biological threats. >> so it became a challeng

would be a lot of long days trying to get through all the potential subjects. >> the focus on steven hatfill the top brass. but in the rank and file, not everyone buys it. >> some of the investigators who really i believe helped turn the tide in the investigation, they were working on their own time. >> working on old leads. including the man nancy haigwood had flagged years earlier. bruce ivins. >> that was years between 2001 and 2004, 2005. he was not an apparent suspect. and then the vice started to squeeze. >> we looked at his e-mails. they boom boomed. he starts to become very interesting to us. >> the e-mails to former colleagues where ivins reveals psychological problems. june 2000, he's taking celexa for depression. but what is really scary is the paranoia. >> we just kept gathering more and more e-mails because he was somebody that neelded more and more scrutiny. >> july 2000, my symptoms may not be those of depression or bipolar disorder. they may be paranoid personality disorder. >> and yet he is -- he's somebody that is working with, you know, some of the most deadly pathogens th