A 33-year-old Fairfax County man was arrested Saturday night in a San Francisco luxury hotel in connection with last week's $50,000 extortion-kidnaping of an Arlington banker's daughter, the FBI said yesterday.

John J. O'Grady, a resident of the Bedford Village apartment in Fairfax County, was met by four San Francisco FBI agents at 11:25 p.m. as he entered his sixth floor, $100-a-night suite at the Fairmont Hotel, the FBI said.

O'Grady will be arraigned before a federal magistrate in San Francisco today in connection with last Tuesday's abduction of Carol Lynn Drewer, 19, daughter of Milton Lee Drewer Jr., president of the First American Bank of Virginia.

O'Grady is charged with violation of the Hobbes Act, which covers extortion through threats of intimidation and violence against financial institutions. The law gives the FBI jurisdiction over such cases.

One Alexandria FBI agent, calling the suspect's actions unbelievably amateurish, said yesterday that "everybody [here] is real shocked that the arrest went down so easy, especially with the penalty this guy may have to pay."

O'Grady is alleged to have abducted Drewer at about 8 a.m. as she left her car in a parking lot at First American's headquarters in McLean where she is employed. Her father later dropped off the ransom payoff, in $50 and $100 bills, near where the abduction occurred, the FBI said. Drewer was subsequently released unharmed at about 10:45 p.m. at a 24-hour convenience store near Seminary Road and Shirley Highway.

The FBI said yesterday the trail that led to the suspect's West Cast hotel room started when agents received an anonymous tip that a nervous man had "dropped a wad of large bills" on the floor last Wednesday morning at Dulles International Airpot.

United Airlines employe Laura O'Connell said a man identifying himself as John J. O'Grady approached a United customer service agent at 8:35 a.m. demanding a ticket on Flight 53, due to depart Dulles 10 minutes later. The man paid for a first class-round-trip ticket costing $898 with $50 bills. O'Connell said. The bills were later traced to the ransom money through their serial numbers, she said.

The same man was stopped at security checkpoint after an X-ray scanner revealed "several metal cylinders" in a small overnight bag. Airport security officers inspected the bag but allowed him to pass, although the man appeared nervous and the cylinders were stuffed with $100 bills, O'Connell said, when the customer service agent heard about the kidnaping on television, that the FBI was notified. Armed with a search warrant, agents searched O'Grady's townsend Street apartment on Friday.

On the flight to San Francisco, O'Grady sat next to a Washington area businessman, and flashed several $50 and $100 bills, according to an investigative source. O'Grady reportedly told the businessman that it was his first trip to San Francisco, and the businessman said he knew an employe at the Fairmont Hotel overlooking posh Nob Hill who could try to arrange accommodations for him there.

O'Grady was picked up at the airport by the hotel employe, identified as Natasha Shiliapnikoff, according to the source. Shliapnikoff, described as an attractive woman in her late twenties reportedly drove o'Grady to the Fairmont and managed to get him a room at the popular hotel, which is usually booked up at this time of year.

When reached by telephone last night at a friend's home in Half Moon Bay, a resort south of San Francisco, Shiliapnikoff declined to discuss her brief encounter with the suspect. "It's my private life. I'd like to keep it that way," she said. "I don't want to get involved . . . call the FBI." Shlianpnikoff was interviewed by the FBI over the weekend, the source said.

Shliapnikoff's roommate invited a reporter into their San Francisco apartment last night, offered him a glass of champagne and recounted how O'Grady visited there one night last week. The roommate, Loretta Contreras, who referred to O'Grady by his nickname, "J.J.," described him as a nice man, and recalled giving him a list of tourist sites to visit during his stay in the city.

While in San Francisco, O'Grady telephoned an acquaintance in Washington and mentioned where he was staying, according to the source. That enabled FBI agents in Alexandria to trace the suspect to the Fairmont, and San Francisco FBI agents were quickly notified. The arrest was made without incident, the FBI said.

San Francisco FBI agents yesterday planned to search a safe deposit box at the Fairmont in hopes of recovering the bulk of the $50,000 ransom.

An investigative source also said yesterday that O'Grady had rented a 1980 orange Chevette to drive to Dulles for the flight to the West Coast. The car was later discovered in the airport's long-term parking lot. Agents found a loaded .22-caliber revolver inside, the source said.

The FBI confirmed Saturday that it was investigating allegations that O'Grady was involved in an earlier kidnap attempt on Drewer five days before last Tuesday's abduction. Sources said that a man with a pistol abducted and sexually assaulted a 26-year-old nursing student in Alexandria, then forced the woman to feign sickness as he unsuccessfully tried to flag down Drewer in her car near her fashionable North Arlington home. When Drewer noticed that the man was armed, she sped away.

Drewer, the third of four children and the only daughter, has been in seclusion and unavailable for comment since the kidnapping. Arlington police said they have increased patrols around the Drewer home since her release.

Yesterday, neighbors expressed shock at the allegations against O'Grady, describing him as an affable man who frequently played frisbee with children at the complex. One Neighbor said O'Grady "frequently helped me with my groceries and I let my 10-year-old son watch football games in his apartment. It's a real shock.

But a young woman, who said she had had drinks with O'Grady a few days before the first kidnaping attempt, said he was secretive about something he had planned.

"He kept talking about the fact that he was going to get even, but he wouldn't tell me even with who or what, just that I would probably hear about it soon."

Neighbors said that O'Grady had lived in the Townsend Street apartment with a roommate for about nine years. Investigative sources also added that O'Grady was believed to be employed in the computer field, but they declined to name a specific firm.