FBI Hunts for 100 People in Probe

As authorities put names Friday to the hijackers who destroyed the World Trade Center and flattened part of the Pentagon, they asked local police to hunt down more than 100 people wanted for questioning about the terrorists and urged everyday Americans to help find anyone who knew them.

“It’s pretty clear that there were probably others involved in these endeavors,” Atty. Gen. John Ashcroft told reporters. “And it’s in our interest to track those individuals down.”

At midafternoon, the FBI in New York placed under arrest a man in custody since Thursday who they said had boarded an aircraft at John F. Kennedy International Airport with a phony pilot’s license. His warrant called him a material witness.

It could mark a significant development in the investigation, because warrants for material witnesses often are used to gain direct information about a crime. Prosecutors obtained the warrant under seal and refused to identify the man or to disclose what he might know about the hijackings.

Justice Department Releases Hijacker Names

The Justice Department made public the names and a smattering of information about the hijackers themselves. All 19 of the names appeared to be Middle Eastern. Law enforcement officials said the hijackers were Saudis, Afghans and citizens of the United Arab Emirates.

Officials said many of the 19 hijackers had lived in Florida. Others were listed as having lived in California, New Jersey, Massachusetts and Arizona. Ashcroft asked that “anyone with information about these individuals immediately contact an FBI field office or call the toll-free hotline.” The FBI said the hotline number is (866) 483-5137.

In addition, federal investigators sent the names of the 100 people who might have specific information about the hijackers to 18,000 police agencies. Ashcroft was careful not to describe the 100 as suspects, but he said they “may have information that could be helpful to us.”

The hijackers took over four airliners filled with passengers Tuesday and piloted two of them directly into the twin towers of the World Trade Center and the third into one of the five sides of the Pentagon. The fourth crashed in western Pennsylvania. The total death toll is expected to exceed 5,000 people.

In the investigation, code-named PENTTBOM and perhaps the biggest criminal probe in U.S. history, there were these additional developments:

* Authorities spoke privately of concern about a potential threat of even more terrorist attacks. They seemed divided over how serious the threats might be, but they were in clear agreement that police vigilance is crucial.

Several law enforcement sources in Washington and New York said they think the attack on the towers accomplished what terrorists attempted eight years ago when they damaged the building in a car bombing, adding that the destruction at the Pentagon signaled that even more ambitious strikes might follow.

They cautioned that future targets might range beyond the East Coast. “There could be up to 30 other targets, and I would think that would be nationally,” one high-ranking law enforcement official said. “You just have to assume there are going to be other targets.”

* Police in Hamburg, Germany, searched 12 apartments and took the wife and child of an unidentified suspect into custody for questioning and protection, but they released an Egyptian arrested earlier this week.

Hamburg police created a 100-person-strong special mobile commando unit to seek out suspected collaborators in the American hijackings. One, a 26-year-old native of Morocco, was being sought on terrorist charges.

* The FBI continued to issue search warrants to major Internet service providers across the United States, and agents pored over voluminous computer logs to gather information about the hijackers.

The warrants were served on America Online Inc., Microsoft Corp. and Yahoo Inc., as well as other companies offering Internet connectivity or related services.

* The agents also analyzed three voice and data recorders recovered from the planes used in the attack. They said they obtained information from one but would not disclose it. Still missing were the data recorder from the jet that crashed in western Pennsylvania and the voice and data boxes from both planes that hit the World Trade Center.

* Agents have traced about $50,000 worth of plane tickets that the hijackers charged on credit cards. The agents scoured financial records, credit card receipts and phone numbers, using sophisticated computer software to quickly link transactions.

In addition to local law enforcement agencies, the FBI sent its list of 100 people wanted for questioning to the airlines, the Federal Aviation Administration, the Border Patrol and other agencies able to help in the search for those named. It did not make the list public.

The so-called “watch list” includes former roommates, possible relatives and people who may have attended flight school with the hijackers, according to a law enforcement official who asked not to be identified.

“They could be virtually anyone whose name we may have but we can’t locate and . . . don’t know the extent of their relationship or what knowledge they could have,” the official said. “Potentially, it could be something serious, but at this point we just want to talk to them.”

In Los Angeles, the destination of three of the hijacked aircraft, virtually all 650 of the local FBI agents were working the case. “This thing is running at full speed and we have every resource working on this,” said Matt McLaughlin, a spokesman for the agency’s Los Angeles office. “We are maintaining a high state of alert as a matter of course.”

Some Fear L.A. Could Be Target

Two federal law enforcement sources said they are concerned that Los Angeles could be a target. They had no information about any threat, but they noted that there had been a foiled attempt to bomb a crowded passenger terminal at Los Angeles International Airport on the eve of the millennium celebrations.

Three men have been convicted in New York federal court for playing a role in that Islamic extremist plot.

In a separate incident at Kennedy airport, two men whom the FBI wanted to question about the attacks on the World Trade Center and the Pentagon managed to board a Los Angeles-bound plane on Thursday despite heavy security.

Ten agents of the Port Authority of New York and New Jersey boarded the aircraft and removed one of the men and a female companion without incident. The second man resisted and had to be subdued before agents took him off the plane, said Justice Department spokeswoman Mindy Tucker.

Both men were released after questioning and it was unclear whether they had any information of value to investigators.

Questions remained, however, about how the men managed to get past security and board the aircraft. They were not considered suspects, but the FBI wanted to talk to both of them, Tucker said. Their names apparently were on a watch list at all U.S. airports.

Federal investigators also have increased their vigilance in Atlanta, telling Associated Press that they have developed information since Tuesday indicating that the city may have been of particular interest to the terrorists.

The officials learned of the alleged focus on Atlanta in FBI interviews of people who knew the hijackers.

Sen. Richard C. Shelby (R-Ala.), the ranking minority member of the Senate Intelligence Committee, declined to discuss what he had learned at intelligence briefings on Friday, but he said Atlanta was a likely target and that other cities might remain in danger.

“Atlanta is a big transportation hub, the largest in the United States, the busiest airport in the United States. It would have to be a target for any terrorist effort,” Shelby said.

“You’ve got to assume there was probably more planned, maybe for the aftershock.”

Investigators Trace Hijackers to Hamburg

In Hamburg, authorities traced two of the hijackers identified by the Justice Department to a nondescript four-story apartment building in a working-class neighborhood south of the Elbe River.

The second-floor hide-out belonging to Mohamed Atta, 33, and his cousin, Marwan Al-Shehhi, 23, had been stripped of belongings and abandoned weeks ago.

Police questioned neighbors, who apparently could tell officers little about the men. Authorities sealed off the apartment, but a missing flap on its mail slot afforded a view into a three-room flat with bare walls and paint-splattered floors bereft of furnishings.

Hildegard Spedovski, who has lived a few hundred feet from the suspects’ building for 46 years, insisted that Hamburg is awash in unsavory figures with links to organized crime and terrorist cells.

“No one protects us,” said the widow.

German authorities concede that the presence of suspected extremists is growing to alarming proportions. After the April arrest of a militant with ties to Osama bin Laden, the Saudi fugitive believed to run a terrorist network from Afghanistan, German Interior Minister Otto Schily told Der Spiegel magazine that Islamic extremists pose “an enormous danger” in Germany.

Federal prosecutor Kay Nehm warned Thursday that more than 3,000 people have been identified as fundamentalist extremists from among Germany’s Islamic population of nearly 3 million.

In the quiet streets of Hamburg, however, suspicion may fall indiscriminately on adherents of Islam--a backlash the peaceful majority fear could subject them to violence or discrimination.

“Of course I’m afraid. People will think because I’m a Muslim that I represent some kind of danger,” said Oezlem Yilmar, a young Turkish immigrant in a blue floral head scarf doing her grocery shopping.

“The terrorists who did these awful things have perverted Islam,” she said.

In Belgium and the Netherlands, police arrested six suspected Islamic militants but made no claims of connection to the trade center and Pentagon attacks. Neither the identities nor the nationalities of the detainees were disclosed.

In France, police were questioning an Algerian arrested last month, and the French newspaper Liberation suggested he was suspected of ties to the U.S. attackers.

In their search of computer logs in the United States, federal agents acted rapidly and declined comment.

“We were contacted by the FBI Tuesday evening,” said Dan Greenfield, vice president for corporate communications at Earthlink Inc. “It was a FISA order, but I don’t know the exact nature of the order.”

FISA, the Foreign Intelligence Surveillance Act, was passed in 1978 during increased concern over terrorism. It established the Foreign Intelligence Surveillance Court within the Justice Department, authorized to handle surveillance and search warrant requests from intelligence agencies and the FBI.

Federal investigators have found that some of the terrorists appear to have had accounts on Web-based e-mail systems such as those offered by Yahoo and Microsoft’s Hotmail.

Such accounts generally offer more anonymity than e-mail received through an Internet service provider, which can usually be tracked to a credit card.

“But those Web mail accounts are not untraceable,” said Elias Levy, chief technology officer of SecurityFocus.com, a computer security firm. Levy is a so-called “white hat” computer hacker who hunts for computer security flaws to help repair them.

Large Internet service providers keep electronic logs of certain activities on their systems that go back months and sometimes years to help solve technical problems, protect themselves legally and track down any outsider who invades their systems.

The Internet trail could fall apart if the terrorists tapped into U.S.-owned Internet systems by first bouncing their requests off Internet computers in countries hostile to the United States, since FBI agents wouldn’t be able to get access to the needed computer logs. Also, using false identities and stolen credit cards could send investigators down a dead end. And accessing the Internet through a public library could provide substantial anonymity to a user.

It also is possible that the terrorists used some type of encryption to conceal what was actually typed in the e-mail. Encryption scrambles a message to make it harder for people who don’t have an electronic “key” to read the data. But simply following the path of messages, their frequency and the flow of traffic can offer investigators the ability to see how the terrorist organization was structured and who was in charge.

“Traffic analysis can tell you if they had a handler and where that handler was located,” Levy said.

‘There Are Lots of Digital Footprints’

Other computer security experts said that the FBI may find mountains of relevant computer logs to track down terrorists responsible for Tuesday’s attacks if service providers still have the information.

“There are lots of digital footprints that anyone using any technology tends to leave,” said John Pescatore, a security analyst for Gartner Group. “Instant messaging channels leave log files lying around.”

E-commerce transactions also leave valuable trails, experts said, but such records are often ephemeral.

“These [terrorists] used the Internet to case the United States over a long period of time,” said Tom Talleur, manager of forensic technology services for the accounting firm KPMG, and former director of NASA’s cyber-crime unit.

Other experts compared computer forensics in this case to traditional detective work.

“You follow clues. It’s gumshoe work. That fact that it’s on a computer doesn’t make it dramatically different,” said Bruce Schneier, chief technology officer of Counterpane Internet Security in San Jose and a noted cryptographer.

“It’s like any other organized-crime [investigation]. . . The challenge is, how far back can you go?”

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Serrano reported from Washington, Williams from Hamburg, Germany. Also contributing to this story were Times staff writers Eric Lichtblau in Washington, Charles Piller in San Francisco and David Wilson, Richard E. Meyer and Tim Rutten in Los Angeles.