A 33-year-old Fairfax County man was arrested last night in a fashionable San Francisco hotel in connection with last week's $50,000 ransom kidnapping here of a county banker's daughter.

John J. O'Grady was arrested about 11:25 p.m. Washington time in his $90-a-day, 6th floor room at the Fairmont Hotel in connection with Tuesday's abduction of Carol Lynn Drewer, daughter of First American Bank president Milton Lee Drewer Jr. The father paid the ransom to free his daughter.

The FBI said interviews with more than 100 persons indicated that the suspect bought a round trip ticket to San Francisco the day after Carol Drewer was released. According to investigators, money used to buy the ticket matched some of the ransom money.

An FBI spokesman here said it was not immediately known if any of the money was recovered at the time of the arrest last night.

Spokesman for the hotel said the arrest of the casually clothed suspect was made without incident after FBI agents knocked on the door of O'Grady's room.

According to the hotel authorities, O'Grady had checked in on Wednesday, but had not yet paid for his lodging.

"We're going to send the bill to the FBI," said hotel security man Jim Bisio.

According to the FBI, O'Grady is charged with violating the Hobbes Act, which governs extortion from financial institutions.

The suspect is expected to be brought before a federal magistrate in San Francisco today.

The banker's daughter, a slightly built, brown-haired woman who works in the marketing department of the First American bank headquarters on Chain Bridge Road in McLean, was abducted by a man as she left her car in the parking lot between 8 and 9 a.m. to go to work.

She was released unharmed by her kidnaper at 10:45 p.m. at a 24-hour convenience store off the Shirley highway interchange with Seminary Road, but only after her father -- without FBI surveillance -- dropped the $50,000 at a prearranged spot near the bank's headquarters.

The FBI yesterday released few details on what originally led a task force involving Arlington, Alexandria, and Fairfax County police to the kidnapping with O'Grady.

"At this time we know nothing about any current or prior employment involving the suspect," an FBI official said, adding that the bureau had no comment on whether O'Grady has a prior criminal record, and whether O'Grady knew the victim personally.

An FBI spokesman yesterday confirmed a previous report that Drewer had been the target of a prior, but unsuccessful kidnaping attempt. The FBI said that O'Grady was believed to have first abducted a student nurse in Alexandria on Sept. 18 in an effort to also kidnap Drewer on the same day.

"Investigations by the Arlington County police department determined that (the Sept. 18 kidnaping attempt) was made by a white male accompanied by a white female attired in a nurse's uniform," the FBI said through a spokesman yesterday.

According to the FBI, O'Grady allegedly abducted the student nurse, blindfolded her, and drove to the Drewer home in the exclusive Chain Bridge Forest subdivision in Arlington. There O'Grady allegedly ordered the nurse to feign sickeness while he flagged down Drewer's car. Drewer slowed her car, but sped off when she saw a weapon inside his waist band, according to FBI.

Later on the 18th, the FBI said, the student nurse told Alexandria police that she had been abducted and sexually assaulted. Five days later, the FBI said, O'Grady manged to kidnap Drewer while her parents were away at a conference in Charlottesville.

Informed sources said that the kidnaping began when the abductor forced Drewer back into her car -- tied and blindfolded her -- and drove her to several First American Bank branches and forced her to write one or two checks on her account. The kidnaper then drove back to the parking lot where he first abducted her. He then forced Drewer into his own car, the source said, and drove off with her again.