WASHINGTON - Federal officials expressed hope yesterday that a Jordanian citizen they arrested Monday in Baltimore would provide crucial information about the Sept. 11 hijackers, whom the man said he roomed with last summer in Northern Virginia.

Officials cautioned, though, that they have no indication the man, Rasmi Al-Shannaq, 27, was involved in plotting the Sept. 11 attacks.

Authorities said they are questioning Al-Shannaq to try to gather any information he has about the hijackers, their habits and means of communication. They also said they hope to find out whether he knows of any attacks being planned.

Al-Shannaq, who authorities said is being held on charges of overstaying his visa, was seized from a house in Highlandtown, in Southeast Baltimore. The raid involved dozens of FBI and other federal agents.

He lived on a quiet block of brown-brick rowhouses, many of which fly American flags. The arrest, residents said, was the talk of the neighborhood.

Some said that in recent months, they noticed heavy traffic to and from the house where Al-Shannaq lives. Most of the visitors, they said, drove cars with Virginia and Washington, D.C., tags.

"They were constantly going in and out of the house," said Dennis Mohr, a neighbor.

Al-Shannaq is one of the few people to emerge from the investigation who seem to have spent much time with any of the 19 hijackers in the United States. Most of the hijackers traveled alone or in tight-knit groups.

Federal officials say Al-Shannaq lived for two months in a Northern Virginia apartment with two of the hijackers, Nawaf Alhazmi and Hani Hanjour, who were on the plane that crashed into the Pentagon.

Officials say Al-Shannaq has been cooperative.

"We are not getting any indication this is a 'Eureka!' situation," one official said. But, the official said, "Any individuals that had any contact with the hijackers, we want to talk to."

It is not clear where Al-Shannaq is being held, and a court date has not been set. Justice Department officials said Al-Shannaq would receive a hearing before an administrative law judge who can decide if he should be released on bond.

FBI agents have been trying to piece together the whereabouts of each of the hijackers leading up to the attacks and to find any roommates or contacts they had. By talking with Al-Shannaq, they want to learn how the two hijackers he lived with could blend into American society while taking part in a complex plot involving dozens of people here and abroad.

It is unclear why it took the FBI until this week to arrest Al-Shannaq.

Officials have previously linked the two hijackers who lived with Al-Shannaq to another Jordanian immigrant who was recently deported. That immigrant, Eyad Alrababah, approached officials after the attacks to say he recognized a published photograph of Alhazmi and had helped him and, officials believe, Hanjour find an apartment in Northern Virginia.

It is not known whether that is the same apartment Al-Shannaq was living in.

Alrababah was deported last month after he admitted that he had helped immigrants fraudulently obtain driver's licenses.

According to the search warrant for Al-Shannaq, obtained by WMAR-TV, federal authorities were seeking four separate Jordanian passports issued in Al-Shannaq's name. Authorities also wanted any "objects relating to the ... illegal issuance of U.S. visas in Doha, Qatar."

Al Shannaq's fiancee said yesterday that she was unaware that Shannaq shared an apartment with the hijackers. She said he came to the United States from Jordan 1 1/2 years ago and in recent months has lived with her, along with his family, in the 600 block of South Lehigh St. in the Highlandtown section of Southeast Baltimore.

"He's very sweet," his fiancee, Marcia Farg, said. "If neighbors were sitting outside, he tried to brighten their day. Anytime anybody asked for a ride, he gave it."

Neighbors said that Al-Shannaq was friendly and almost always said hello. Ron Mathers said he occasionally spoke with Al-Shannaq and lent him tools to use on his car.

"He was mild-mannered," Mathers said. "You couldn't help but like him in a way."

Early last month, Al-Shannaq took a job at Nino's, a pizza restaurant in Parkville. The owner and manager there said they were shocked that one of their former employees could have known any of the hijackers.

Though they trusted Al-Shannaq to carry the shop's money on deliveries, they fired Al-Shannaq last week because he was unreliable, said Anna Savini, the manager.

Savini said she could not imagine that Al-Shannaq would be involved in a terrorist plot.

"He couldn't be a part of anything like that," she said. "He was too lazy."

Sun staff writer Josh Mitchell contributed to this article.