The first piece of evidence linking the suspects in the US terrorist attacks to the man Washington says is the mastermind emerged over the weekend.
Funds were reportedly transferred in the days preceding the attacks from the Dubai account of a known associate of Osama bin Laden to Muhammad Atta, the kingpin of the operation. Atta and two other suspects returned unspent monies to that account just before the suicide mission.
This evidence came to light just as a picture of 19 hijackers began to develop. This group seems to have been tight and highly integrated rather than part of a sprawling network of many cells.
Atta, an Egyptian who studied in Hamburg, apparently recruited the other leading figures, Ziad Jarrah, a secular Lebanese, and Marwan al-Shehi, from Ras al-Khaimah in the United Arab Emirates.
These three are believed to have piloted the planes. The fourth pilot was Hani Hanjour, a Saudi from the hill town of Taif who lived in the US off and on for more than a decade. Contrary to initial reports, none of the pilots had worked for the Saudi national carrier or brought wives and children to the US.
The four leading figures were reasonably well educated, experienced, worldly men who contrasted with the raw recruits who provided the "muscle" during the hijackings. At least 10 of these men were Saudis, eight of them from the kingdom's poorer provinces of Baha and Asir which they left last December.
Several had claimed they were going to fight in Chechnya. Most had little English and were dependent on the organisers for logistics.
The true identities of as many as four suspects remain disputed. In one case, a Saudi who is alive and well said his name and birthdate had been appropriated.
In another, the photo distributed by the US authorities was of a Saudi youth from Mecca who is a computer programmer working in that city.
This means there is still confusion about the membership of the cell. Confusion over identities is compounded by the fact that the hijackers did not explain their motives.
The five-page handwritten document which investigators said they found in the effects of Atta and another suspect, and also at a crash site, is not illuminating. The document consists of instructions laced with the odd Americanism and verses from the Koran.
