WASHINGTON - The money came from Afghanistan. The plot was likely hatched in Germany. And the 19 young men who carried out the catastrophic suicide attacks acted largely alone inside the United States, leaving behind few co-conspirators.
One month, 655 arrests and nearly 300,000 tips after the deadly hijackings of Sept. 11, that is the rough outline of how investigators increasingly believe the attacks were planned and executed, according to interviews, court records and other public documents.
As they have emerged over the past four weeks, the details of the plan appear to have been as extraordinarily simple as they were deadly. With a few flying lessons, lax airport security and access to public computers and U.S. banks, the hijackers were able to exploit America's openness with relative ease.
Determining who else may have been involved has proved more difficult. More than 600 people have been arrested or detained in the United States; 200 others are wanted for questioning. President Bush unveiled a list of the world's 22 most-wanted terrorists at FBI headquarters yesterday. While top officials have called Saudi militant Osama bin Laden the mastermind, no one has been charged with helping plan or carry out the attacks.
"We're four weeks into the investigation with a long, long way to go," a senior U.S. law enforcement official said yesterday. "We've probably discounted as much information as we've verified."
The largest criminal investigation in U.S. history has been overshadowed this week by the military strikes in Afghanistan, stirring questions of whether the Bush administration's priority in its war on terrorism is military victory or courtroom justice.
A senior investigator acknowledged yesterday that the role of law enforcement is only one piece of the response to last month's attacks, along with diplomatic, financial, intelligence and military efforts.
And Bush said yesterday that the focus must not be solely on the military activity.
"The American people must understand that we're making great progress on other fronts - that we're halting [the terrorists'] money, that we've got allies around the world helping us close the net," Bush said.
Bush emphasized the search for perpetrators overseas as he announced the creation of the most-wanted terrorists list. It is an expansion of the FBI's famous 10 most-wanted list, which is credited with aiding in the capture of 438 of 467 fugitives who have made the list since 1950.
Bin Laden, already one of the 10 most-wanted, also led the terrorist list along with two of his chief advisers, Mohammed Atef and Ayman al-Zawahiri. Both appeared in a videotaped statement by bin Laden widely televised on Sunday. All three are suspected of helping design the Sept. 11 attacks in New York and Washington that left nearly 5,400 people dead or missing.
Although bin Laden has been named by American and British officials as the chief architect of last month's attacks, he was listed yesterday as being sought in the bombings of the U.S. embassies in Kenya and Tanzania in 1998.
In addition to 13 men wanted in the African embassy bombings, others were named in connection with the 1993 World Trade Center bombing, the bombing of the Khobar Towers military barracks in Saudi Arabia in 1996, and the hijacking of a TWA flight in 1985 in which a Navy diver on board - Robert Dean Stethem of Waldorf, Md. - was tortured and murdered.
None of the 22 terrorists was named in connection with the events of Sept. 11. However, senior law enforcement officials said several of the men on the list may be linked to last month's attacks, though they declined to say which ones.
Secretary of State Colin L. Powell, who appeared at the FBI event with Bush, said many of the individuals being sought are part of the leadership of the al-Qaida terrorist network.
"They have blood on their hands from Sept. 11, and from other acts against America in Kenya, Tanzania and Yemen," Powell said.
Information released by the British government says that at least three of the 19 suicide hijackers are members of al-Qaida and that at least one of the men played a key role in both the bombing attacks on the embassies in East Africa and the attack last fall on the USS Cole as it refueled in Yemen.
Investigators over the past month have focused most on the reputed leader of the hijackers, Mohamed Atta. The 33-year-old son of a Cairo lawyer, Atta became increasingly devout while a college student in Hamburg, Germany, and that is where investigators believe the hijacking plan might have been formed.
Two of Atta's ex-roommates in Germany - Marwan al-Shehhi and Ziad Samir Jarrah - also are on the list of suspected hijackers.
German investigators were in Washington yesterday, meeting with U.S. law enforcement authorities. Officials with the Justice Department described the meetings as a normal part of the sweeping inquiry, and would not describe what was being discussed.
Attorney General John Ashcroft has said publicly that investigators believe the roots of the attack can be traced to Afghanistan and to Europe. To find out who might have helped the hijackers, investigators have closely tracked the movements of the men in the weeks and months before the attacks, as well as the money trail.
The investigation has stretched from Europe to Florida to Maryland, where the five hijackers aboard American Airlines Flight 77, which crashed into the Pentagon, spent time in the weeks before the attacks working out at a Gold's Gym in Greenbelt and shopping at a nearby Giant Food store.
Atta has been the central figure. But the activities of other suspected hijackers also are under close scrutiny. Of particular interest are Khalid Almihdhar and Nawaf Alhazmi, two of the hijackers on the Pentagon flight, who were on a State Department watch list of known terrorists in the months before the attacks.
Information about most of the more than 600 people arrested or detained remains elusive. Many of them have provided no helpful information. In northern Kentucky last week, FBI officials acknowledged that tips that led to the arrests of more than two dozen individuals from Mauritania in northern Africa turned out to be mistaken, and the individuals were released.
Still, court records indicate that some potentially important figures have surfaced.
In Virginia, federal authorities arrested an Alexandria man whose name and telephone number appeared on a street map left in Alhazmi's car at the parking lot of Washington Dulles International Airport. The man, Mohamed Abdi, has been described by prosecutors as a material witness in the investigation and "possibly more."
Another material witness in the case is Zacarias Moussaoui, who was jailed in Minnesota on a passport violation at the time of the attacks, but who had raised suspicions months earlier when he told instructors at an Eagan, Minn., flight school that he wanted to learn how to steer large airliners, but not how to take off or to land.
U.S. authorities also are questioning two men arrested on an Amtrak train days after the attacks who carried hair dye, box cutters and thousands of dollars in cash. Ayub Ali Khan and Mohammed Azmath had been on a cross-country flight that left from Newark, N.J., on Sept. 11. It was grounded in St. Louis that morning, after the attacks on the World Trade Center and the Pentagon.
Another figure in the case is an Algerian pilot named Lofti Raissi, currently detained in London, who British prosecutors described as a lead flight instructor for several of the hijackers.
In recent weeks, much of the investigative activity has been centered overseas. The White House has said that 150 suspected terrorists or their supporters have been arrested abroad, and the State Department said yesterday that dozens more had been detained in 23 countries.
To identify and locate suspects, particularly the 22 men whose names and photos were put on the FBI's terrorism list yesterday, federal investigators are considering publishing leaflets or matchbooks with the information about the fugitives to be distributed overseas.
They also have invoked one other tried-and-true incentive: money. The State Department has about $25 million available for its rewards program. Congress is considering putting up even more to help apprehend fugitive terrorists, whose capture could help investigators solve the Sept. 11 attacks or prevent new violence.
"What we're talking about isn't a bounty. We're not encouraging bounty hunting here," a senior State Department official said. "We're paying for information on their whereabouts. We want the information. We don't want the head."