WASHINGTON -- Attorney General John Ashcroft on Tuesday vowed to wage a "concerted national assault" on terrorists as he expanded the investigation of last week's twin attacks to marshal the resources of every U.S. attorney in the country.
Aided by a federal grand jury in New York, the investigation had detained 75 people for questioning and had four people under arrest as material witnesses, law enforcement officials said.
The government also announced a new policy that gives immigration authorities 48 hours, or longer in emergencies, to decide whether to charge an alien with status violations, up from 24 hours. Many of those questioned in Tuesday's attack were being detained on immigration violations.
The attorney general vowed to use "every legal means at our disposal to prevent further terrorist activity by taking people into custody who have violated the law and who may pose a threat to America."
Ashcroft said publicly for the first time that authorities are probing whether more flights beyond the four that crashed last Tuesday were targeted for hijackings, but noted the possibility had not yet been corroborated.
The restructuring of the investigation includes the creation of anti-terrorism task forces by every U.S. attorney office in the country.
"These task forces will be a part of a national network that will coordinate the dissemination of information and the development of a strategy to disrupt, dismantle and punish terrorist organizations throughout the country," he said.
The government searched for more than 190 people who investigators believe may have information about the attack or who may have assisted the hijackers.
The effort was being aided by a grand jury in White Plains, N.Y., and officials said other grand juries would likely be used around the country to issue subpoenas and gather evidence.
Detroit men arrested
Meanwhile, three Detroit men were arrested Tuesday on charges of identity fraud and misuse of visas. Court records said the FBI seized documents suggesting the men worked in food preparation for airlines at Detroit Metropolitan Airport and collected information about an American military base in Turkey, a U.S. foreign minister, an airport in Jordan and diagrams of aircraft location and runways.
Federal documents identified the men as Karim Koubriti, 23; Ahmed Hannan, 33; and Farouk Ali-Haimoud, 21.
Among the four material witnesses under arrest was Albader Alhazmi, 34, a Saudi national and Saudi-trained doctor who was doing a medical residency in radiology at University of Texas Health Science Center, a law enforcement official said. He was being held in New York.
Alhazmi did not show up for his radiologist job on Sept. 11. He had been working at a military hospital located on Lackland Air Force Base in San Antonio during the week before the attacks, said an official at the medical center.
Meanwhile, evidence emerged Tuesday that the FBI had tracked the activities of one Arab man who was seeking jetliner training from Minnesota to Oklahoma in the weeks before Tuesday's attacks.
The FBI came by 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 issues after he aroused suspicions by seeking to buy time on a flight simulator for jetliners at a Minnesota flight school, law enforcement officials said. 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.
Possible Iraqi link
An unconfirmed link to Iraq emerged Tuesday in the intelligence community. A U.S. official, speaking on condition of anonymity, said the United States has received information from a foreign intelligence service that Mohamed Atta, a hijacker aboard one of the planes that slammed into the World Trade Center, met earlier this year in Europe with an Iraqi intelligence agent.
The raw intelligence came in since the attacks last Tuesday and has not yet been corroborated by U.S. authorities, the official said.
The FBI continued to explore evidence, some which has emerged from Saudi Arabian authorities, that some of the hijackers may have stole the identities of other Arabs and used the names to carry out their attacks, officials said.
Authorities also detained a man in San Diego, Calif., who was linked through financial transactions to two of the 19 hijackers, officials said.
Also in California, investigators are questioning a foreign national who may have been a roommate of a suspected hijacker in last week's terrorist attacks. Tarek Mohamed Fayad, 33, was taken into federal custody Monday in Los Angeles.
In other developments:
The FBI has asked U.S. banks and foreign banks with U.S. operations to report transactions in their records by individuals who have been named as under investigation in connection with the attacks.
FBI cybercrime specialists have tracked down hundreds of e-mails from the hijackers and their associates, who used both public and private e-mail systems to communicate, an FBI official said, speaking on condition of anonymity.
Associated Press Writer John Solomon contributed to this report.