US investigators believe they have found the "smoking gun" linking Osama bin Laden to the Sept. 11 terrorist attacks, with the discovery of financial evidence showing money transfers between the hijackers and a bin Laden aide in the United Arab Emirates.
The man at the center of the financial web is believed to be Sheikh Saeed, also known as Mustafa Mohamed Ahmad, who worked as a financial manager for bin Laden when the Saudi exile was based in Sudan, and is still a trusted paymaster in bin Laden's al-Qaeda organization.
Money transfers have been traced to Florida on Sept. 8 and 9, from an account under Ahmad's name in Dubai to Mohamed Atta, the ringleader among the 19 hijackers who took part in the attacks.
Atta and other hijackers sent money back to an account under the same name before their suicide mission. The money is presumed to be unused "change" from the operational fund, which investigators say stretched to about US$500,000.
The return of unused funds by the hijackers is a trademark of the al-Qaeda organization, which has been prepared to pay large sums of money on big operations, but which is extraordinarily stingy over the expenses of its suicide bombers.
The UAE central bank has ordered the freezing of all accounts under Ahmad's name as well as accounts linked to 25 other people and organizations named by the US Treasury last week as suspected elements in al-Qaeda.
US intelligence has been virtually certain from the day of the attacks that the atrocity was carried out at bin Laden's behest. But the financial strands linking the hijackers to a bin Laden aide provide hard evidence which will be crucial in the continuing effort to maintain an international coalition behind the US-led military effort once fighting starts.
Until the money trail was uncovered, the evidence pointing to bin Laden was persuasive but largely circumstantial. German intelligence had intercepted messages between al-Qaeda members on Sept. 11 celebrating the attack in a manner that suggested prior knowledge.
Foreign intelligence agencies had also helped the CIA trace the paths of some suspects back to Afghanistan. On Sept. 15 it was reported that, according to a Middle Eastern intelligence agency, one of the hijackers, Wail al-Shehri, from Saudi Arabia, had trained in bin Laden's al-Farouq training camp. On Saturday an intelligence source quoted by CNN went further and said that at least four of the hijackers had trained in bin Laden camps in Afghanistan.
However, with the FBI now pursuing more than 100,000 leads as they home in on the operation's international cash flow, an electronic trail is being revealed which investigators believe represents far more direct evidence of bin Laden's role as financier and coordinator.
"The main link is a strictly financial flow. Atta is involved and he looks like the principal among the people here," said a US intelligence source familiar with the investigation. He said the cash flowed from Ahmad, the suspected paymaster in the UAE to Germany and the US, to Florida in particular, where several of the hijackers learnt to fly and lived in the run-up to the attack.
The UAE information minister, Sheikh Abdullah bin Zaid al-Nahayan, said a man with a Saudi Arabian passport left the UAE on the day of the attack for Karachi in Pakistan, after receiving transfers of "surplus" funds of US$15,000 from three hijackers, Mohamed Atta, Walid al-Shehri and Marwan al-Shehhi. The money was transferred from the US to the UAE two days before the attack. "This is too much of a coincidence," Sheikh Abdullah said.



