OLNBROOK, England, Sept. 29 — Three months before the terrorist attacks on the World Trade Center and the Pentagon, Lotfi Raissi, who the authorities allege was involved in planning the attacks, moved into an apartment here with his wife. They were a mystery to their neighbors in the small complex and to shopkeepers a block away, avoiding all conversation and even eye contact, neighbors said today.

Mr. Raissi put up his own satellite dish, though several were already at the complex. He said he needed one strong enough to receive programs from the United States and Germany, a next door neighbor said today.

Mr. Raissi chose to live near Heathrow Airport, and his neighbors often saw him leaving for the 20- minute bus ride to the airport. Those trips were to the United States as part of the final preparations for the terrorist attacks on Sept. 11, a British prosecutor said at an extradition proceeding for Mr. Raissi in a London court on Friday.

"His job was to ensure the pilots were capable and trained," the prosecutor, Arvinda Sambir, said.

If Mr. Raissi did help manage the hijackers, an accounting of his movements and activities would help show how the operation was organized.

Ms. Sambir said that Mr. Raissi helped train four of the hijackers but indicated that his main responsibility was Hani Hanjour, who the F.B.I. says piloted that plane that hit the Pentagon. Mr. Raissi's contacts with the pilots may have begun in March 2000, but his most frequent trips to the United States were in June and July, the prosecutor said.

"We have sufficient evidence to show not just association with the pilots," Ms. Sambir said. "It goes further than that. We have evidence of active conspiracy providing correspondence and telecommunications with them as well as video footage of them together."

The prosecutor said the evidence against Mr. Raissi included video footage of him and Mr. Hanjour traveling to Arizona. (During one visit to Arizona in July, Mr. Raissi received a speeding ticket, which said he was going 89 miles per hour in a 65 m.p.h. zone.)

It is not clear how Mr. Raissi was able to travel to and from the United States with such ease or what kind of visa he had. A spokesman for the American Embassy in London said it was not possible on a Saturday to determine whether the consular section had issued him a visa.

In court on Friday, Mr. Raissi, through his lawyer, denied any connection with the attacks.

Mr. Raissi's family has also strongly denied the accusation, contending that he is a bona fide pilot who has flown jets in the United States and is receiving further training. After the police searched his home for two days and removed flying manuals, Mr. Raissi's uncle, Kamal Raissi, told reporters: "Of course, Lotfi has flying manuals at home. He is learning to be a pilot."

Details of Mr. Raissi's background remain sketchy. He was born in Algeria in April 1974. He is married to a French woman, who was working for Air France and was arrested along with her husband a week ago. She has been released and no charges have been filed against her.

It is not known when Mr. Raissi moved to Britain, but in 1993, he was convicted of theft in Uxbridge, England, according to an F.B.I. affidavit in the extradition proceeding here. At the time, he used an alias, Vincent Fa Brice, the affidavit says.

He appears to have moved to Phoenix in 1997, according to public records, which indicated that he lived in 3 apartments in 14 months. In April 2000, he received a pilot's license, listing his address as Dely Brahim, Algeria, according to Federal Aviation Administration records.

Sylvia Stinson, the chief flight instructor at the Sawyer School of Aviation in Phoenix from December 1997 to July 2000, said she remembered Mr. Raissi training with others.

"They would practice on the flight simulator, and it was not unusual for one of them to do the instructing," Ms. Stinson said.

On a trip to the United States last June, he renewed his pilot's license but gave his address this time as 7 Cavendish Court, Coleridge Crescent. In fact, the town is Colnbrook. The street is Coleridge Crescent, and the complex is Cavendish Court. That is where he was living when he was arrested.

Mr. Raissi's next door neighbor, Paul Hanley, said today that since Mr. Raissi moved in there had been a constant flow of men in and out of the apartment and that sometimes the talking was so loud that neighbors asked them to be quiet.

That was about the limit of their contact. "You'd make eye contact with him to say good morning, and he'd look the other way, so you got the impression he didn't want to talk to anyone," Mr. Hanley said.