For the last three months, the defendant who has drawn the most attention in a terror trial under way in Manhattan federal court is Lynne F. Stewart, who made a name as a defense lawyer for suspects accused of terrorism. But as the prosecutors' case has unfolded, most of the evidence about the international conspiracy they hope to prove has centered on a defendant who sits silently beside her, Ahmed Abdel Sattar. A Staten Island postal worker and a Muslim, Mr. Sattar served as a paralegal aide for Ms. Stewart in the 1995 trial of Sheik Omar Abdel Rahman, the...