As more is learned about how the Sept. 11 hijackings were financed, authorities are showing some success in cutting off sources of terror money, with $6 million blocked and 50 bank accounts frozen so far. 

Meanwhile, the State Department issued a public announcement cautioning Americans in Italy that "symbols of American capitalism" may be targets of terrorist attacks in the coming month.

U.S. investigators believe they have traced wire transfers from one of the terrorists to Mustafah Ahmed, a man from the United Arab Emirates who disappeared the day of the attacks.

Mohamed Atta, a suspected leader of the hijacking teams, received $100,000 sent from Pakistan, said a law enforcement source speaking Monday on condition of anonymity.

Atta wired money to Ahmed on Sept. 8 and Sept. 9, possibly returning unused funds from the hijacking plot, the source said. Atta is thought to have been the pilot of one of the planes that hit the World Trade Center in New York. Four U.S. airliners were commandeered in all; more than 6,000 people were killed when the planes crashed.

President Bush, who on Monday announced the progress in shutting down the funding pipeline, said there were 30 frozen accounts in this country and 20 overseas.

"And we're just beginning," Bush said a week after he announced an executive order that would freeze any U.S. assets of Usama bin Laden and 26 other people and organizations.

In the order, which barred Americans from doing business with any of the named individuals or organizations, Bush also promised to shut down U.S. operations of foreign banks that conduct business with bin Laden or his associates.

Soon after, foreign ministers from the seven leading industrialized nations — Japan, Germany, Britain, France, Italy, Canada, along with the United States — agreed to produce a coordinated plan to freeze the assets of terrorist organizations.

The Treasury Department has said it was reviewing additional individuals and groups as possible additions to the list.

The money trail in the United States also led to Punta Gorda, Fla., where the owner of a mail service business said Atta and another person bought $100-to-$200 money orders at her store from four to six times from mid-July to mid-August.

Jean Waldorf, owner of The Shipping Post, said she did not know how the money was spent.

"He was not a friendly person," she said of Atta. "There was no please, thank you or have a nice day. The main reason I recognized him was his eyes. When he looked at you it was as if he was looking straight through you, very cold, no emotions."

Evidence Mounts Against Bin Laden

The United States gave "clear and compelling evidence" Tuesday that bin Laden was involved in last month's attacks, NATO's secretary-general said.

Investigators also said they intercepted a call from bin Laden to his adopted mother Sept. 9, in which bin Laden said "in two days you're going to hear big news and you're not going to hear from me for a while."

Held for Questioning

While arrests and interrogations spread abroad, three college students were transferred from San Diego to New York for questioning and a U.S. magistrate in Alexandria, Va., ordered a man and woman held without bond.

The students were Osama Awadallah, Mohdar Abdullah and Yazeed Al-Salmi. The name and phone number of at least one of the students was found in a Toyota Corolla registered to Nawas Alhazmi, one of the 19 suspected hijackers, according to published reports.

The two Virginia residents were held without bond pending hearings Wednesday.

Magistrate Barry Poretz ordered Luis Martinez-Flores, 28, of Falls Church, and Kenys Galicia, who works in Falls Church, detained followed a brief hearing in U.S. District Court.

According to an FBI statement unsealed Monday, Martinez-Flores was charged Friday with falsely certifying that Hani Hanjour and Khalid Almihdhar lived at his Falls Church address. The certifications were on state registration forms needed by the two to obtain Virginia ID cards. They were aboard American Airlines Flight 77, which crashed into the Pentagon.

Galicia was accused by the FBI of assisting numerous people in obtaining false Virginia documents. The FBI said she admitted on Sept. 19 that she signed residency certification forms for two of the suspected hijackers, Abdulaziz Alomari and Ahmed Saleh Alghamdi.

U.S. authorities also arrested a man who was released by Pakistan after 14 years in custody for a 1986 hijacking. Attorney General John Ashcroft said Zayd Hassan Abd Al-Latif Masud Al Safarini was arrested Friday after he was released in Pakistan.

He was expected to be returned to Washington to face a 1991 U.S. indictment for the same Sept. 5, 1986, hijacking in Karachi in which 22 passengers were killed, including two U.S. citizens.

Showing the magnitude of the investigation so far, the Justice Department said it has analyzed 241 threats deemed serious and credible. Over 4,400 subpoenas were issued and more than 500 people have been arrested or detained, including 145 people held on immigration violations.

The Associated Press contributed to this report.