Central casting, no doubt, would have preferred a saturnine young conspirator with a well-muscled body and a gaze of ice. But if the FBI has it right, the mastermind behind last February's bombing of the World Trade Center is Sheik Omar Abdel Rahman, 55, a lumpy, blind cleric who suffers from diabetes and is so frail he can barely walk.

As enigmatic as the Sphinx, the Egyptian militant has emerged as a galvanizing figure in a new world disorder that threatens to bring international terrorism to America's doorstep. Currently in a Manhattan jail awaiting trial on federal charges that he conspired with 14 of his followers to "wage a war of urban terrorism against the United States," Sheik Omar insists he is innocent. "I did not give orders," he has said. "I have nothing to do with anything."

Egyptian and American authorities disagree. A decade ago in Cairo, Sheik Omar was acquitted of charges that he had sanctioned the 1981 assassination of President Anwar el-Sadat. Even so, the U.S. State Department put him on its list of suspected terrorists. Then in 1990 a series of bureaucratic foul-ups enabled him to enter the United States—where he even managed to get a green card.

Since then, his followers have been linked to the murder of Jewish militant Meir Kahane, the World Trade Center bombing and a foiled plot to blow up several New York City landmarks, including the United Nations Building and the Hudson River tunnels. The Sheik steadfastly denies all knowledge of these plots. "How can we conspire against this nation," he said in a recent jailhouse interview, "while we are here enjoying your water and food?"