<p>HAGERSTOWN, Md. (AP) — The FBI, revisiting an old lead in the anthrax investigation, recently interviewed a former Fort Detrick researcher and his co-workers about his whereabouts when the letters were mailed, he and his lawyer said Sunday.</p>
<p>Ayaad Assaad, who now works for the federal Environmental Protection Agency, said the agents also quizzed him Tuesday about his knowledge of producing finely powdered anthrax like that used in the letters.</p>