On Nov. 29, 1999, a 31-year-old architecture student in Germany named Mohamed Atta, unknown to the world, but already determined to strike an unforgettable blow against those he believed to be his enemies, boarded Turkish Airlines flight 1662 from Istanbul to Karachi, Pakistan.
Atta took at least a couple of days to reach his final destination: a training camp in Afghanistan run by al-Qaida, Osama bin Laden's sprawling, international terrorist organization.
There, investigators say, Atta was accorded the greatest honor that a soldier in the international Islamic army can receive: an audience with bin Laden himself.
Atta's visit with bin Laden, which has not been disclosed previously, is among the latest discoveries by American investigators trying to reconstruct the hijacking plot that brought so much death and havoc to the United States. The investigators believe that Atta was accompanied by other leaders of the plot and that they talked to bin Laden about undertaking a terrorist operation.
The new information, much of it gleaned from interviews with Qaida members captured in Afghanistan and Pakistan, provides the strongest evidence that bin Laden personally supported the 19 men who carried out the deadliest foreign attack on American soil.
Over the last year, investigators have reached other conclusions as well. They have identified several figures aside from the hijackers who seemed to form a penumbra of support for the terrorist network, serving as recruiters, messengers and handlers of the $500,000 to $600,000 needed to carry out the attacks. Atta himself has emerged as an even more important organizer than was previously known, a figure who might not have created the plot, but who took early command of it and was viewed, in the words of one of the other hijackers, as "the boss."
Foreign intelligence officials also say that one of the most important supporters, Ramzi bin al-Shibh, who lived with Atta in Hamburg and accompanied him to Afghanistan, was present at a critical meeting in early 2000 in Malaysia, which was attended by two other al-Qaida operatives who later formed the core of one of the hijacking teams. Bin al-Shibh's presence at the meeting is the earliest known link between Atta's Hamburg team, which included three of the suicide-hijacker pilots, trained mainly in Florida, and the men who commandeered the fourth plane, who trained in California and Arizona.
In addition, American law enforcement officials have become increasingly confident that a 37-year-old Kuwaiti, Khalid Shaik Mohammed, was one of the plot's central planners. Interviews with Qaida prisoners, including Abu Zubaydah, the highest-ranking operative in custody, have confirmed the suspicions about Mohammed, whom investigators believe is an uncle of Ramzi Yousef, the convicted mastermind of the attack on the World Trade Center in 1993.
This new information, disclosed by officials as the anniversary approaches, helps fill in significant gaps in the narrative of what happened that Tuesday, helping explain a diabolical plot that involved years of planning and training across three continents yet required nothing more to execute than 19 driven and suicidal men, a half million dollars and a handful of knives.
In the days after the attacks, government investigators quickly determined many details of the plot, including the identities of all the hijackers and their itineraries from several points around the globe to flights schools in Florida, California and Arizona and then to their targets in the United States.
But much else about Sept. 11 remained mysterious. Investigators were sure from the beginning that bin Laden and al-Qaida were ultimately behind it, but they did not know who exercised practical control, when and where the plot was hatched or how al-Qaida recruited and maintained contact with the killers. Even now, they have not filled in all the gaps.
"There are many aspects of the plot that we'll never know unless you get a participant to tell you when it began and how it was put together," said one senior American law-enforcement official.
But in the year since Sept. 11, investigators have pored over cell phone records, flight manifests, financial receipts and interviews with captured al-Qaida members to develop a richer picture of the plot, particularly how it came together overseas.
One general conclusion that can be drawn is this: The attacks last year were the deadly outgrowth of a series of terrorist efforts that began with the truck bombing of the World Trade Center in 1993 and a foiled plot two years later in the Philippines, where terrorists schemed to blow up a dozen American airliners as they crossed the Pacific.
The investigation in this sense has not turned up evidence that the same groups were responsible for all those plots, but rather that there is a kind of interlocking terrorist directorate, with one group taking the baton from another, and one group's goals becoming those of the next group.
The form of terrorism that struck on Sept. 11 involves a still shadowy and fluid network of people and groups, and it clearly shows that since the mid-1990s, many parts of that network have gravitated toward al-Qaida. The attack on the United States, with three separate groups of young men from scattered places coming together, was the culmination of that process.
A WEDDING IN HAMBURG
In October 1999, at the radical al-Quds mosque in Hamburg, Germany, several men attended the wedding of Said Bahaji, a German-born Muslim of Moroccan descent, who is believed to have been in charge of logistics for the local cell of al-Qaida. Looking back, investigators see it as a gathering of the most important of the Sept. 11 terrorist teams just as the plotting began.
Among the men at the wedding were Atta, who was from a middle-class family in Egypt; Ziad Jarrahi, who had left his native Lebanon in April 1996, to fulfill a dream of studying aeronautical engineering in Europe; and Marwan al-Shehhi, a citizen of the United Arab Emirates who, also arriving in Germany in 1996, seems to have been almost inseparable from Atta. Investigators believe that the men were at the controls of three of the four planes that were commandeered.
Others were at the ceremony as well, men from several countries who, investigators believe, were part of the plot's network of support.
Among them, for example, was a 300-pound German of Moroccan ancestry named Mohammed Heidar Zammar, who is believed to have recruited for al-Qaida among the young radical Muslims who prayed at the al-Quds mosque. Another was bin al-Shibh of Yemen, the Atta roommate who would probably have been among the suicide-hijackers, except his repeated applications for visas to the United States were rejected.
In fact, the men almost surely knew one another for a year or so before the Bahaji wedding, which was when Atta, bin al-Shibh and Bahaji signed a lease for an apartment at 54 Marienstrasse, a narrow, sloping street in a working class suburb of Hamburg. According to the investigators, it was when the men became roommates that the plan to take some action together in the service of Islamic holy war began to be formed.
"For us, the decisive moment is the move into the Marienstrasse 54," Kay Nehm, Germany's general prosecutor, said in a recent German television interview. "This is when there were intensive discussions concentrating on the question of what can be done. The hate was there, the hate against the U.S., the hate against international Judaism. Those were the discussion topics, and then they say, 'Actually, we have to do something."'
In forming a terrorist cell in Hamburg, Atta and company were doing what radical young Muslims were doing across the globe, participating in a movement whose chief backer and inspiration was the renegade Saudi millionaire bin Laden.
A few months before the Bahaji wedding, in February 1998, bin Laden had issued a well-publicized fatwa, or Muslim religious order, calling on all Muslims to "comply with God's order to kill the Americans and plunder their money wherever and whenever they find it."
Then, in August 1998, al-Qaida succeeded in simultaneous truck bombings of the American embassies in Nairobi and Dar Es Salaam, killing 250 people, including 11 Americans, events that no doubt electrified the members of al-Qaida cells in other countries.
In addition, Hamburg and specifically the al-Quds mosque were important centers for recruitment into the radical Muslim cause. And because there are no strong signs that Atta, al-Shehhi or Jarrahi, were Islamic radicals before they arrived in Germany as students, it seems safe to assume that they were recruited into the cause locally, possibly by Zammar.
"The typical pattern of recruitment is that the recruiters find you," said Magnus Ranstorp, an expert in terrorism at the Center for the Study of Terrorism and Political Violence at the University of St. Andrews in Scotland. "They are talent spotters. You go to a radical mosque, they notice you." The first litmus test, Ranstorp said, is a show of religious devotion, specifically a willingness to regularly attend morning prayers, held at 5 a.m.
"Then they conduct background checks," Ranstorp said. "Then comes the test for psychological strength — commitment is not enough."
The presence of all these men at the wedding of Bahaji has led investigators to believe that the plan to attack the United States had essentially been formed by then, a bit under two years before Sept. 11, 2001. A videotape of the wedding obtained by German officials shows bin al-Shibh speaking of the "danger" posed by Jews, and then he recited a paean to holy war, or jihad, against the supposed enemies of Islam.
Soon after the wedding of Bahaji, who fled Germany after Sept. 11, the men in the Hamburg cell began to take concrete steps to put a plan into effect. Most important, according to German investigators, all three of the Hamburg hijackers plus bin al-Shibh and Bahaji went to Afghanistan for training in an al-Qaida camp.
Klaus Ulrich Kersten, director of Germany's federal anti-crime agency, the Bundeskriminalamt, said the men were all in Afghanistan from late 1999 until early in 2000.
THE PHILIPPINE CONNECTION
In going to Afghanistan, the members of the Hamburg cell entered into a culture of holy war that was already well established. The Muslim men who journeyed to Afghanistan to join al-Qaida went through a similar, demanding program of basic military training. Then, those who showed exceptional promise were singled out for special missions, including what were called martyrdom operations, like the 1998 African embassy bombings, or the attacks on the United States.
That pattern seems to have been broken in at least a minor way in connection with the Hamburg group, which arrived in Afghanistan together and was allowed to stay together. Did Atta and company already know precisely what mission they would undertake? Or did the specific plan to hijack airliners and use them to attack targets in the United States come from the al-Qaida leadership itself?
Mohammed, the Kuwaiti whom some investigators now see as one of the main planners of Sept. 11, is a man with a past that connects him to other efforts to inflict maximum harm on the United States.
In 1995, he was in Manila, Philippines, where he was close to Ramzi Yousef, the mastermind of the 1993 World Trade Center attack and a man who was planning, before he was forced to escape the Philippines, to blow up a dozen American airliners over the Pacific on the same day.
Among the notes found in Yousef's computer after his sudden flight from the Philippines was the outline of a plan to hijack an American airliner and crash it into the headquarters of the CIA.
Yousef was captured a few weeks after he left the Philippines, but Mohammed has remained at large and, while there are no signs that he and Yousef were members of al-Qaida at that time, investigators believe Mohammed became an important figure in al-Qaida later.
Some investigators think that Atta and other midlevel al-Qaida members could have devised the plot and brought it top leaders for approval. But most American and German investigators believe that the plan originated with Mohammed or others in Afghanistan and that Atta became involved after he conveyed a message that he wanted to carry out a terrorist attack.
If that assumption is true, these investigators say, Atta and his associates went to Afghanistan for training by al-Qaida, which presented them a plan inspired both by the 1993 World Trade Center attack and Yousef's scheme of using a hijacked airliner to attack the CIA. The investigators think that senior Qaida leaders then deemed Atta and the others up to the job and entrusted it to them.
"We know that the initial decision to carry out a terrorist act came from Afghanistan, more specifically from the top al-Qaida leadership," the German investigator, Kersten, said. "We believe too that there were then further phases, when the plans were made more precise, not only in Germany, and involving many other people."
Atta himself was a near perfect person to carry out the plot. He had no record of terrorist activities, and so he would not be under suspicion by Western intelligence agencies. He was well-educated and spoke both German and English fluently, enabling him to operate without difficulty in the United States. And he was a grimly determined man, disciplined, reliable, and not likely to flinch.
In recent weeks, U.S. officials say, some al-Qaida members being interrogated in Guantanamo Bay, Cuba, and elsewhere have confirmed that Atta and some of his associates met with bin Laden while they were in Afghanistan. That would have been consistent with the standard practice in al-Qaida camps where an audience with bin Laden was regarded as a high honor reserved for those selected for important missions.
When the Hamburg men returned to Germany toward the end of February 2000, they began sending e-mail messages to ask for information from 31 flight schools in the United States.
Nehm, the German prosecutor, described a conversation in which al-Shehhi mentioned the World Trade Center to a Hamburg librarian, in April or May 2000 and boasted: "There will be thousands of dead. You will all think of me."
"You will see," Nehm quoted al-Shehhi as saying. "In America something is going to happen. There will be many people killed."
A MEETING IN MALAYSIA
Two months after the wedding in Hamburg and halfway around the world, a group of seven or eight Muslim militants got together in Kuala Lumpur, Malaysia, at the apartment of a local supporter of al-Qaida. The CIA, which had learned of the meeting in advance, tipped off Malaysian intelligence, which secretly photographed it. Two of the men photographed, Khalid Almidhar and Nawaq Alhazmi, would later be among the 19 hijackers.
Malaysian intelligence had no listening devices planted at the meeting, so it is not clear what its main purpose was. The main item on the agenda may have been the plans for an attack on an American naval vessel. One of the men present in Kuala Lumpur was later implicated in the attack on the USS Cole, which took place in October 2000.
But it is possible that the emerging plans for an assault on American territory were also discussed. American officials have said they are not certain that bin al-Shibh was there, but in recent interviews, foreign investigators, who have seen the photographs of the Kuala Lumpur meeting, say they are convinced that he was. Credit card records also indicate that bin al-Shibh was in Malaysia at the time of the meeting.
The signs also are strong that just after the Kuala Lumpur meeting, Almidhar and Alhazmi had become part of the Sept. 11 plan. A few weeks later, in January 2000, the two men became the first of the suicide-hijackers to land in the United States, arriving in Los Angeles on a flight from Bangkok. Within weeks, the two of them registered at a flight school in San Diego and began learning to fly, though they showed very little aptitude for it and were soon dropped by the flight instructor.
Why did the plot involve two separate groups, one that prepared in California and one in Florida, where Atta, al-Shehhi, and Jarrahi arrived a few months later?
One possibility is that Almidhar and Alhazmi were better known within al-Qaida than any of the young men from Hamburg. Intelligence officials say that Almidhar's father-in-law ran a safe house in Yemen that relayed messages between Qaida leaders and operatives. Qaida leaders may have wanted the hijackers to enter from two separate tracks for added security, and it is possible that Almidhar and Alhazmi were supposed to keep an eye on Atta himself from enough of a distance so as not to arouse the suspicion of American law enforcement authorities and to report on him to al-Qaida headquarters in Afghanistan.
At some point, Almidhar and Alhazmi were joined by Hani Hanjour, a 29-year-old member of a well-off Saudi family. Hanjour is believed to have been the pilot of United Flight 77, which was hijacked after taking off from Dulles Airport and was used to crash into the Pentagon. He had been in the United States since 1996, when he attended a flying school in Scottsdale, Ariz. Despite a poor record as a student, he was able to get a commercial pilot's license in 1999.
Almidhar and Alhazmi settled into San Diego, attending activities at the local Islamic Center. Almidhar also traveled extensively outside the United States, but Alhazmi seems to have stayed put. He even advertised for a wife on an Arab-language Internet dating service and received two replies — an odd thing for a man on a suicide mission to do.
The members of the Hamburg group arrived in the United States several months after the Malaysian group. Al-Shehhi was first, arriving in Newark, N.J., on May 29. Atta came on June 3, also through Newark, but in another of the unresolved mysteries in the case, he arrived via Prague, where he took considerable trouble to go. He first went to Prague via airplane, but was turned away because he did not have a valid visa. He went back to Germany on the first flight, obtaineda visa in Bonn and then returned to Prague by bus. He stayed just one night there and left for the United States the next day.
Several weeks later, on June 27, Jarrahi arrived in Atlanta on a flight from Munich.
Within a few weeks of their arrival, all three undertook the first task of the plot: they took flying lessons at various academies, getting their licenses around the end of 2000. After learning to fly small planes, all the men paid for time on a simulator, learning the techniques of flying bigger planes, specifically wide-bodied Boeing passenger jets.
Then, in the first half of 2001, all three members of the Hamburg contingent traveled several times outside the United States. Early in January, for example, Atta made a short trip to Spain. He made a second trip to Spain in July, going via Zurich where, according to one government document, he bought a knife. Bin al-Shibh was there at the same time, according to the Spanish police.
Aside from whatever role he played in planning the attacks, bin al-Shibh was apparently the operation's coordinator and paymaster. Shortly after Atta and al-Shehhi arrived in Florida, bin al-Shibh wired roughly $115,000 to their accounts at the Sun Trust Bank there.
According to officials of the Czech Interior Ministry, Atta made another trip to Prague in April 2001, and while he was there, the Czechs said, he met with an Iraqi intelligence agent named Ahmed Khalil Ibrahim Samir al-Ani. But some American investigators doubt this account. Those who believe he did go to Prague and meet al-Ani note that the Czech interior minister, Stanislav Gross, has reaffirmed it several times.
Those who are skeptical say that no American immigration records show Atta traveling outside the United States in April. And in the Czech Republic, some intelligence officials say that the source of the alleged meeting was an Arab informant who approached the Czech intelligence service with his sighting of Atta only after Atta's photograph had appeared in newspapers over the world. It is possible that the informant mistook another man for Atta, and many investigators now lean to the conclusion that the meeting never took place.
A CONVERGENCE IN AMERICA
When Atta returned to Florida from Spain on July 19 the plot swung into its final phase. Over the next several weeks, 13 men, all of them Saudi Arabians, entered the country, all on valid visas to join Atta, the three other pilots, and Alhazmi and Almidhar.
The 13 men came to provide muscle for the plot, helping execute the hijackings and keeping passengers and crew at bay while the newly trained pilots flew the planes to their targets. It seems likely that the Saudis were among the legions of young Muslim men who went to Afghanistan in response to the call to make holy war against the enemies of Islam.
In previous al-Qaida operations — most important, the 1998 African embassy bombings — those entrusted on missions were chosen from among the recruits training in the camps in Afghanistan. And some investigators believe that Zubaydah, who ran the training camps before his capture and is the highest-ranking Qaida leader under interrogation, may have played a role in selecting them.
At about this time, one other mysterious figure entered the picture, a French-Moroccan Muslim named Zacarias Moussaoui. He was arrested in August in Minnesota after instructors at a flight school reported to the FBI that he was behaving suspiciously. Federal prosecutors say that Moussaoui also received money transfers from bin al-Shibh, and they contend that he was to have been the 20th hijacker, the replacement for bin al-Shibh, who had been unable to get into the United States.
But investigators concede that it is also possible that Moussaoui was training for a separate mission.
COUNTDOWN TO GROUND ZERO
In the final few weeks before the attacks, the 19 men busied themselves with practical details. Many of the Saudis opened bank accounts at the Sun Trust Bank. They got driver's licenses, satisfying the airlines' requirement that all passengers show government-issued photo ID's before boarding a plane.
Several of the men obtained Virginia identification cards via a black market that operated out of a parking lot in Arlington, Va. To maintain discipline and to stay in good condition, most of the men got temporary memberships in health clubs in Florida.
Then, over the course of the summer, the various teams went to separate locations on the East Coast. One group took up residence at motels in Laurel, Md., not far from Dulles International Airport, where one of the four planes was hijacked. Several other men rented an apartment in Paterson, N.J., just across the river from Manhattan where they would have had distant views of their main target, the World Trade Center. Others, including Atta, continued to live in Florida.
Airline, rental car, and cell phone records show that Atta was furiously busy. He rented cars often and put thousands of miles on them. American officials say that he also made regular trips from Florida to Newark, presumably to meet with the group in Paterson.
Because some of those living in Paterson had come across the country from California, it may have been on one these trips that the Florida group and the California group began to coordinate their plans. The FBI has also noticed "spikes" in cell phone use at what seem to be key points in the plan — for example, just after the arrest of Moussaoui and just before the men began, in late August, to buy tickets for the flights they would hijack.
Investigators found that members of both the Florida and California teams were in Las Vegas in August, and they believe that final plans may have been coordinated then, including, quite possibly, what flights to hijack and which team members would be on which flight.
As Sept. 11 neared, the teams were geographically in place. The men who hijacked American Airlines 77 from Dulles Airport was installed in Laurel, those who seized United Airlines 93 at hotels near Newark, most of the 10 men who hijacked two planes at Boston's Logan Airport at a hotel in downtown Boston.
In one of the most mysterious aspects of the plot, Atta and one of the Saudi recruits, Abdulaziz Alomari, drove to Portland, Me., on the night of Sept. 10. The two men stayed in a motel in Portland and took an early morning commuter flight to Boston the next day.
In doing so, they took a risk. They did not have much time to make the connection from their commuter flight to United Airlines flight 11, the flight they commandeered. Indeed, the connection was so close that, had the commuter flight been at all late, they would have missed the very flight they intended to hijack, even as their confederates coming from downtown Boston were already assembled at Logan Airport.
There have been many theories of this: that they made contact with a confederate in Portland who gave them the final go-ahead; or more likely that by arriving on a connecting flight, they would avoid the security check in Boston. None of those explanations seems entirely satisfactory, especially given the risk and especially given that only Atta and Alomari, who were on the same hijack team, took the steps they did. Whatever their motivation, it apparently did not apply to the three other teams.
Perhaps the best explanation is that Atta saw arriving on a connecting flight in Boston as a kind of insurance policy. Assuming that security procedures were less rigorous at a smaller airport, he may have believed that he and Alomari had a better chance of getting their knives through the checkpoint than in Boston. That would mean that, even if all the other team members failed in their assigned tasks, at least Atta and one confederate would succeed in theirs.
It was perhaps a final measure of Atta's determination and fanaticism. If the plot succeeded in hijacking only one plane and flying it to its target, he wanted to be sure that it was the plane he was on.
On the last night, the suicide-hijackers were supposed to read some handwritten instructions that Atta had distributed to them. The instructions told the men to shave excess hair from their bodies, to read certain passages of the Quran, and to remember that the most beautiful virgins, "the women of paradise," awaited the martyrs of Islam. "When the confrontation begins," the instructions continued, "strike like champions who do not want to go back to this world."
The men who waited to strike and to die were near the end of a long journey. Atta had gone from Cairo to Hamburg to Afghanistan to the Czech Republic, to Switzerland to Spain and, of course, to the United States. Others came from Saudi Arabia, Yemen, Lebanon, the United Arab Republic; they had passed through Malaysia, Thailand and states of the Persian Gulf on their way to what would come to be called ground zero.
There the complex plot to murder Americans in fulfillment of Osama bin Laden's fatwa "to kill the Americans and their allies" would take its terrible toll of thousands of unsuspecting men and women who got up on Sept. 11 to go to work or to travel on airplanes and who died before the morning was over.