Though conduct of the nationwide investigation remains largely secret, emerging details from various law enforcement documents and sources sketch out the dimensions of a manhunt sweeping up vast collections of evidence and raw information. The data are fragmentary, and it is not clear if any suspects have potentially criminal connections to terrorists, including the Sept. 11 hijackers.
But the information contains scores of leads--from the alarming to the bizarre--and underlines the massive task federal agents face as they try to pinpoint potential threats. The urgent effort has resulted in hundreds of arrests and extensive seizures of property such as computer hard drives and knife-equipped cigarette lighters.
Authorities in the United States and Canada are still seeking for questioning scores of individuals identified in the documents.
Among them are three Saudi brothers the reports say are directly connected to associates of Bin Ladin. All three have been frequent visitors to the United States. The youngest is a pilot and the eldest studied aircraft maintenance in Arizona, but authorities appear to be most concerned about the middle brother, 26, who previously resided in Arizona and Oregon.
The middle brother was described as knowledgeable about weapons systems and infiltrating the United States. According to law enforcement reports, he boasted of fighting in jihads in Bosnia and the Philippines, and had agreed to assist a suspected Bin Laden operative with information about the U.S. Southwest, including the nation's borders and potential terrorist targets there.
Others sought for questioning or further investigation in the Southwest include a 36-year-old Arizona man from Yemen. One investigative report described him as a radical Muslim who had dropped out of sight in late August. He was a licensed pilot and had his mail forwarded to the home of another man who was identified as the target of several international terrorism investigations.
And agents were trying to locate a Tennessee-based Saudi businessman who was trying to buy small planes in late August. There was no indication the businessman was involved with any of the hijackers or other suspected terrorists.
In New York, a Staten Island postal worker who once was photographed with Bin Laden was being sought. He has been missing since Sept. 11. In Houston, two Middle Eastern men attending flight school were being sought after they abandoned the apartment and personal belongings they shared eight days before the Sept. 11 hijackings. Agents confiscated a computer for investigation.
The FBI was trying to trace a report that five Saudi men who were booked to fly from Los Angeles to New York a week before the attack had their reservations made from Florida by one of the 19 suspected hijackers. At least four of the Saudi passengers also were licensed pilots.
In Canada, U.S. agents were briefed on a 36-year-old Kuwaiti man in whose belongings were discovered documents that identified specific buildings in an Ottawa government complex--notably the atomic energy building and the virus and disease control labs.
Among the more curious cases under investigation was that of a Saudi language student in Florida linked to the e-mail address Last--Day--11. The youth had moved and closed his bank account in Fort Lauderdale before agents could question him about similarities between the e-mail address and the Sept. 11 terrorist date. Separately, federal agents also were seeking the pilot father of a second-grade student who told a teacher last summer that his family was moving to Florida and that his dad, a Saudi citizen, "crashes planes into big buildings."
A computer repair shop in Louisiana called in federal agents when technicians working on a customer's troubled hard drive reported finding electronic traces of efforts to hack into sensitive federal aviation computer systems. Apparently arousing curiosity at the shop was the discovery that from July 20 to Sept. 11 the computer owner also had been tracking certain airline flights, including those that were hijacked by terrorists.
Additional reports also show that investigators have developed new information related to some of those arrested or detained since Sept. 11.
Among them is Nabil A. Al-Marabh, 34, the Kuwait-born former Boston cabdriver arrested near Chicago during a national manhunt. A confessed terrorist in Jordan identified Al-Marabh as a conspirator in the foiled millennium plot to bomb tourist sites in Amman, Jordan and Los Angeles International Airport on New Year's Eve 1999.
Al-Marabh has "known connections" with Bin Laden, according to the reports. He said he was in Afghanistan from 1991 to 1994. He is suspected of illegally crossing the border with Canada on various occasions. Sources also said Al-Marabh failed a polygraph test. Any connection to the hijackers remains unclear.
When arrested, Al-Marabh possessed an array of identification--including driver's licenses from Michigan, Massachusetts and Ontario, Canada, two expired U.S. immigration work permits and a Syrian passport.
In Ohio, FBI agents looking for possible associates of one hijacker encountered a 30-year-old Syrian immigrant in Akron managing a gas station. The man's girlfriend told investigators he was such a supporter of Bin Laden that he wanted to name their child Osama.
A search of the gas station and the man's home yielded cigarette lighters with concealed knives, three computers and videos of buildings, bridges and power plants in Washington, Chicago, Cleveland, and Niagra Falls, N.Y., reports said. Later, the man was judged deceptive during a polygraph exam. He was being held for alleged immigration violations.
Elsewhere, investigators detained a Saudi Arabian in Detroit who was encountered videotaping a federal building. An Afghani national who applied for a crop duster license was given polygraph examination, as was a Maryland friend of one of the 19 hijackers. Neither passed conclusively, according to the reports.
Agents also arrested an Egyptian with ties to suspected hijacker Hani Hanjour. He "showed strong deception" in a polygraph exam, according to one report, and was being held in a Maryland county jail on unrelated trespassing charges.
Another flagged for "deceptive" answers was a Saudi airline employee who was questioned after the FBI stopped him in Las Vegas two days after the terrorist attack. The 44-year-old man was about to board a flight destined for Hamburg, Germany. He was described as a former Continental Airlines employee who lived for a time near San Diego. One report said he was attempting to recruit Muslim youth to travel to Afghanistan and support the Taliban.
Investigators also were on the lookout for threats from outside the continent. According to one investigative report, several Lebanon-based men have been identified as potential terrorists because they have "expressed willingness to carry out suicide missions . . . against Israeli and U.S. targets."