Authorities believe at least five men held in New York in the wake of the Sept. 11 attacks may have vital information about the terror plot — but the five aren't talking.

So investigators have focused on gathering information from more distant associates of the hijackers and poring over telephone and bank records to build criminal cases against the men.

Authorities hope to convince them that cooperating with the investigation is the only alternative to a long prison sentence, said federal officials familiar with the investigation who spoke to The Associated Press on condition of anonymity.

Investigators believe at least some of the five "can provide us with some pretty good information to shed light on all this," a senior official said. "Based on our investigation, we speculate that these people have knowledge and can help us."

Like the more than 1,000 people detained in the terror investigation — including as many as 100 in New York City — the men have not been directly charged in the attacks. Instead, some key figures in the investigation have been held on material witness warrants, which allow authorities to arrest someone considered crucial to an investigation without charging them.

Three of the five men — Zacarias Moussaoui, Mohammed Jaweed Azmath and Ayub Ali Khan — are being held as material witnesses. Another, Osama Awadallah, was initially held as a material witness but was indicted this week on perjury charges. The fifth, Nabil Al-Marabh, faces immigration charges.

Only Awadallah, originally held as a material witness, has appeared in open court in New York. His lawyer, Jesse Berman, insisted he had "nothing to do with the terrible things that happened on Sept. 11."

But investigators have singled Awadallah and the four others because they suspect they either had direct contact with — or even assisted — the 19 hijackers of four planes and the intricate plot carried out after years of preparation, one federal official said. All are being held at a federal lockup in lower Manhattan.

Drawing the most attention is Moussaoui, who was detained in August in Minnesota after authorities learned he sought training on how to fly large jetliners, but not on takeoffs or landings.

"We don't know if he was going to do something himself or was part of the original plot, but we have strong suspicions about him," the senior official said.

Azmath and Khan were detained a day after the attacks in Texas, where they had traveled by train after their airline flight was grounded. They came under suspicion when they were found to be carrying box cutters, hair dye and $5,000 in cash, and because their bodies apparently were shaved. That detail was consistent with documents recovered from the luggage of Mohamed Atta, suspected ringleader of the hijackers, telling hijackers to shave excess hair from their bodies.

The men's clean-shaven bodies "raised suspicions that they were planning another hijacking," the senior official said.

Al-Marabh, a former Boston cab driver, has ties to an Usama bin Laden associate, Raed Hijazi, who is jailed in Jordan on charges that he planned to blow up a hotel filled with Americans and Israelis on New Year's Day 2000. Court documents filed in Canada in the terror investigation say Al-Marabh himself has ties to bin Laden's Al Qaeda terrorist organization.

Awadallah, a Jordanian who studied at a college in San Diego, is accused of lying to a grand jury about his association with two hijackers aboard the plane that hit the Pentagon.

The federal officials said they were neither surprised nor discouraged by the silence of the men in custody. Over time, the officials said, the sprawling federal investigation should produce enough evidence to persuade the suspects to cooperate.

George Andrew, a retired deputy head of counter-terrorism in New York for the FBI, said investigators typically do surveillance and background checks on terror suspects before they are taken into custody, "stacking the decks before they even begin to talk to them."

The urgency of the terrorism threat has taken away that luxury.

"What we like to do is bring in as much information against the guy that we can gather to give him reason to speak, recreate his steps for the last month or the year," he said. "Give us time and we'll do it."