Money is allegedly gathered through a series of Islamic foundations and organizations operating as bin Laden fronts around the globe - even in the United States.
Dr. Ayman al-Zawahiri, bin Laden's second-in-command and likely successor, appears on the Bush administration's list of people and groups with possible ties to terrorism. CBS News has learned al-Zawahiri, under an assumed name, visited the United States at least twice in the last decade on fund-raising tours of California mosques. On one trip, his men trained at a flight school near San Jose.
Also on the list, the Alkifah Refugee Center used to recruit Mujahadeen in Brooklyn. That group has been tied to the 1993 World Trade Center bombing. Its director, Wadih El Hage, later became bin Laden's personal secretary. He awaits sentencing in connection with the U.S. Embassy Bombings in Kenya and Tanzania.
On Saturday, agents from a federal antiterrorism task force arrested an El Hage associate, Ghassan Dahduli, for refusing to talk to investigators about the attacks on New York and Washington.
Dahduli reportedly once worked for the Dallas-based Internet company InfoCom. Just six days before the attacks, federal agents raided InfoCom and revoked the company's right to continue exporting technology to Libya and Syria.
Dahduli also once worked for the Islamic Association for Palestine. The IAP and its sister organization, the Texas-based Holy Land Foundation, have been linked to terrorist groups in the past. On the same day as the InfoCom raid, a federal grand jury demanded the groups' records.
The IAP and Holy Land were founded and funded by Mousa abu Marzook, a major investor in InfoCom. He's also the political leader of the terrorist group Hamas.
InfoCom, and both Islamic organizations, deny any ties to terrorists and condemn the raids.
"I never raised any money in United States. I never sent any money out of United States," Mazook told the CBS News program 60 Minutes in a 1996 interview.
Nihad Awad of the Council on American-Islamic Relations considers the scrutiny by U.S. officials an attack on civil liberties. "It takes us back to the McCarthy era, which I believe is scary for all of us."
Federal officials say those fears have protected some groups.
"We have been fighting this campaign with one arm behind our backs because there was a very valid concern about infringing on the rights of Muslims," says Mike Ackerman, a former CIA officer.
Investigators say most American Muslims do not willingly donate to terrorist groups. Many are never aware that their good intentions can become weapons for terrorists.
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