His mother attributes his headstrong personality to his having to assume a father-figure role to his younger siblings because Sheik Gulshair was away so often doing missionary work.
After he started traveling to Pakistan and Afghanistan, however, Shukrijumah began to change, say friends and associates interviewed by the FBI. He would take off for long periods, to places overseas he would not discuss.
"Every time he came back, he was a different person," the FBI official said. "He was more calm, more cool and more purposeful in his actions."
By 2001, the FBI was investigating Shukrijumah in connection with two suspected terrorist plots, one of which involved a group apparently using South Florida as a base from which to recruit militants and finance attacks and assassinations in the Middle East.
But agents were never able to connect him to either plot. They later came to believe that he had been deliberately keeping his distance because, as one agent put it, "it was felt in the [Al Qaeda] community that he was in for bigger and better things."
After the Sept. 11 attacks, federal agents swarmed South Florida looking for clues and connections they might have missed. As many as 15 of the hijackers had spent their last months there, training for and planning the suicide mission.
The FBI ultimately took several of Shukrijumah's acquaintances into custody on terrorism or immigration charges.
Agents also went looking for Shukrijumah. But by then, he was gone and had left few clues.
'He Could Be Anywhere'
When Shukrijumah reemerged in the FBI's consciousness in March 2003, Pasquale "Pat" D'Amuro, then the FBI's senior counter-terrorism official and a veteran Al Qaeda tracker, felt an acute sense of dread.
"We thought he was a grave danger to the security of the United States," D'Amuro recalled recently. "We thought he could be anywhere."
On March 20, 2003, the same day the U.S. began bombing Iraq, the FBI went public. With TV news crews on their heels, more than 50 federal agents and local police officers descended on Shukrijumah's neighborhood.
Armed with a warrant for his arrest as a material witness, FBI agents knocked on doors, showing photographs and asking whether he had been seen in Florida recently.
They scoured his mail, credit cards, bank records and phone bills.
By then, however, Shukrijumah had been away from his family home for almost two years.
In the months before Sept. 11, he had traveled widely through the United States and Canada, scouting potential terrorist targets, say FBI officials, who believe he spent about a week each in New York, Washington, Chicago and Montreal.
Since the attacks, her son had called just once, to check in, Zuhrah Abdu Ahmed told the agents.
The agents asked whether her son knew lead hijacker Mohamed Atta and others she had seen on TV. They wanted to know whether he had ever mentioned Al Qaeda or trips to Pakistan and Afghanistan.
Ahmed said her memory was hazy, but she insisted that her son was innocent.
Sitting on the front stoop of the family home, Ahmed -- a tiny woman with warm brown eyes and a big smile, dressed in a flowing black robe and head scarf -- said her son didn't like South Florida's freewheeling singles scene and the nightclubs and bikinis.
"But he like America so much," she said. "People, he say, [are] very nice and kind. If only they more decent, he say, this would be the best place on Earth."
Ahmed, whose husband died in 2004, conceded that it was possible her son might have fallen in with the wrong crowd.
"I recognize a lot of people do evil stuff in the name of the religion," she said, and then paused. "He's a young guy. Maybe they try to trap him, without he even knew what was going on around him. Who knows?"
The FBI also began chasing Shukrijumah through the back alleys of cyberspace. Within hours of the FBI's public announcement, Shukrijumah might have given them a lead.
Just after midnight that day, an e-mail popped up in the guestbook section of MasterArabic.com, a website that Shukrijumah had set up to promote his father's Arabic tutoring business and Islamic teachings. Routed to obscure the identity of the sender, the message said only, "I am safe."
Tracking Down Leads
In their hunt for Shukrijumah, the FBI dispatched teams of agents to Saudi Arabia, Morocco and Yemen, where he had relatives. Agents also tracked leads through Europe, Asia and South America.
One of those leads took them to Charlieville, Trinidad, where a Muslim cleric had called federal agents to say Shukrijumah was traveling to and from the island and "had company." Agents fanned out across the dirt streets of Charlieville and found several men Shukrijumah had spent time with.
One of them, Imtiaz Mohammed, told The Times recently that he had two lengthy, sometimes testy, interviews with FBI agents. He told them that he, Shukrijumah and others in Trinidad did talk about world politics, but that Shukrijumah never said anything suggesting he was a militant, and never explained his travels.
