Four people have been arrested as material witnesses and 75 others are being questioned in the rapidly expanding investigation into last week's attacks, Attorney General John Ashcroft said Tuesday, as authorities filed the first criminal charges after finding three men in a house with false immigration papers and airport diagrams.
The arrests in Michigan occurred when FBI agents raided a residence in Detroit looking for one of the nearly 200 witnesses being sought in the investigation. Instead, they found the three men with airport-related diagrams and documents about a military base and the "American foreign minister," according to an FBI affidavit.
The affidavit did not explain the reference to "foreign minister." The three were charged with having false immigration papers.
From the information they've gathered from intelligence intercepts, witness interviews and hijackers' cars and homes, authorities are becoming more and more certain that a second wave of violence was planned by collaborators, with Sept. 22 an important date in the evidence.
Tuesday's attacks were "part of a larger plan with other terrorism acts, not necessarily hijacking of airplanes. Those acts were going to occur in the United States and elsewhere in the world," Sen. Bob Graham, D-Fla., chairman of the Senate Intelligence Committee, said.
Law enforcement sources declined to be more specific, and an FBI spokeswoman would neither confirm nor deny the the report to FOXNews.com.
Ashcroft confirmed the FBI was investigating troubling reports that at least one more airliner was set to be hijacked by the terrorists. Investigators are carefully looking at the names on a flight that was scheduled to leave Boston 30 minutes after the second doomed airlines left, but was canceled because of mechanical problems.
Vowing to use "every legal means at our disposal" to prevent further attacks, Ashcroft announced that suspected illegal aliens can now be detained for 48 hours, double the old period. He also announced the government will also create an anti-terrorism task force, with offices in several in major cities.
In yet another revelation, government sources confirmed they were told this summer by another foreign intelligence group that Mohammed Atta met with an Iraqi intelligence officer some months ago. Officials are convinced Atta had a key role in the hijackings.
Also Tuesday, a federal grand jury was convened to investigate the terrorist attack that destroyed the World Trade Center. It was not immediately clear whether the grand jury would also investigate the attack against the Pentagon, and the hijacking that ended in a crash in Shanksville, Pa.
One of the four material witnesses detained is Albader Alhamzi, 34, a Saudi national and Saudi-trained doctor who was doing a medical residency in radiology at the University of Texas Health Science Center, said one of the government officials, speaking on condition of anonymity. Alhamzi was being held in New York.
Authorities also detained a man in San Diego who was linked through financial transactions to two of the 19 hijackers, officials said. They declined to say whether he was arrested as a material witness.
More details emerged Tuesday about law enforcement activity in the weeks leading up to the attacks, which the U.S. government has said it had no advance warning of.
The FBI visited the Airman Flight School in Norman, Okla., about two weeks before the terrorist attacks, inquiring about Zacarias Moussaoui, who is now in custody in New York in the investigation.
The FBI had a picture of Moussaoui and asked if people at the school could identify him and they also asked about his mannerisms and what he did at the school, said admissions director Brenda Keene.
Moussaoui was detained Aug. 17 in Minnesota on immigration concerns after he aroused suspicions by seeking to buy time on a flight simulator for jetliners at a Minnesota flight school, law enforcement officials said. The Oklahoma school officials described Moussaoui as an impatient student who was not good at flying. But they said nothing about him led them to think he was connected to terrorists.
This week, federal investigators in California took custody of a foreign national, Tarek Mohamed Fayad, 33, who may have had links to one of the hijackers, a sheriff's department official in Los Angeles County said. Fayad had been detained for five days by immigration officials.
Law enforcement officials continued the hunt Tuesday for 190 others who may have information about last week's terrorist attacks.
They had their work cut out for them: Attempts to find these accomplices may be being thwarted by what seems to be an intentional "disinformation" campaign, Fox News has learned.
Eyes on bin Laden
On Monday, Secretary of State Colin Powell said "all roads point to bin Laden" — the multimillionaire Saudi extremist suspected of sponsoring a worldwide terrorist network that recently warned of massive attacks against the U.S.
The Taliban has asserted that bin Laden is not behind the attacks, citing a lack of resources. They also warned of "revenge" if Afghanistan is attacked.
Early evidence, including communications between bin Laden supporters discussing Tuesday's attacks, indicated the hijackers were tied to the suspected terror mastermind.
On Tuesday, Japanese, German and American investigators were looking into claims of suspicious stock selling ahead of the suicide strikes in New York and Washington.
Investigators were reportedly focusing their attention on the possibility that bin Laden's contacts predicted their attacks would send markets reeling worldwide and profited by short-selling stocks.
Officials also said authorities were gathering evidence about four terrorist cells that may have had prior involvement in earlier plots against the U.S. Those include the USS Cole bombing in Yemen, the 1998 attacks on U.S. embassies in Africa and the foiled attack on U.S. soil during the millennium celebrations, all of which are linked to bin Laden.
Fox News' Carl Cameron, Rita Cosby and the Associated Press contributed to this report.