Just before a car carrying Washington lobbyist Merle D. Baumgart plunged from the George Washington Memorial Parkway into the Potomac River two years ago, the woman driving the car felt a "thump" and a sharp pull to the right on her wheels, according to her sworn testimony in a civil suit.

Joan C. Paszek, who said she was driving Baumgart home from Washington's Rotunda Restaurant, stated in a deposition filed in a U.S. District Court case here that she was driving in the right lane toward McLean when a car going in the same direction passed her on the left.

As the car passed, she felt a thump. "It was a thump, and all of a sudden my car was -- not the mechanism, I would not say that - but I felt a pull on my wheels. What caused the pull on my wheels, I don't know," Paszek said.

Paszek said she did not know whether the other car had hit her. "At the time, my attention was on my car and in maintaining control of my car," she said.

"I felt a thump; I then proceeded, or landed, in the Potomac," she testified.

The death of Baumgart, who was working for the American Bankersp Association and had worked for Rep. Peter J. Rodino (D-N.J.), has been under investigation by a Justice Department organized crime stirke force because of the possibility it might be connected with organized crime activities.

The strike force, headed by prosecutor John Dowd, also has been probing the possibility that Interstate Commerce Commission officials Robert L. Oswald and Richard W. Kyle might have passed inside information on ICC decisions to trucking firms with organized crime ties, sources within the ICC have said.

In addition, the strike force, reportedly is interested in relationships - through third parties - among Baumgart, Oswald and Alexei A. Goodarzi.

Goodarzi was the maitre d' at the Rotunda. He was murdered last month.

However, no evidence has been developed to indicate that the three cases are in any way related. "Since these people moved in the same circles, it would be surprising if they didn't know each other or have friends in common," a Justice prosecutor involved in the case said.

Baumgart's death in the early morning hours of May 20, 1975, orginially raised suspicions of foul play because of a bizarre incident Baumgart reported to police and friends 10 days earlier.

Baumgart said he was driving along the same stretch of the parkway where he was later to meet his death when two men in two cars forced him to the side of the road. One of the men bashed in his windows with a baseball bat, Baumgart said. He managed to escape only by reversing direction and driving the wrong way up an access roadway, he reported.

Baumgart later described himself to a superior at the bankers' group as being "scared to death."

U.S. Park Police, who recovered Baumgart's body from the water, initially believed the incident probably was an accident. Paszek, who emerged almost unscathed from the car, did not permit press interviews.

Her detailed account of the incident and the events leading up to its is contained in a 123-page deposition made last year in a negligence suit filed against her by Baumgart's estate. The case was settled when Paszek agreed to pay Baumgart's two sons $18,000.

In the deposition, Paszek, at the time a 27-year-old draftsman for Wooward & Lothrop, said she first met Baumgart, who was separted from his wife, through her roommate. She saw him at the Rotunda five months before the incident and a second time at a party before night of the fatal accident, she said.

Paszek testified that she initiated the final meeting by saying she wanted to obtain advice from the 40-year-old Baumgart on pursuing a career in the investment field. The two had drinks at the Greenery, the Democratic Club, and the Rotunda, where they had dinner until 1:30 a.m., she said.

Paszek said she could not recall any details about the car that passed her on the parkway. "I know by the time I was going downhill that the car was going up the hill, but that is all I can recall," she said.

After emerging from the car, Paszek said she attempted to search for Baumgart by walking around the shore and calling his name. She said she then hailed passing motorists for help.

The two men who stopped for her, Bryan Murphy and Michael Chauvin, told The Washington Post several months after the incident that the woman they picked up - who turned out to be Paszek - did not tell them that anyone was in the car with her.

"I asked her if anyone was in the car," Chauvin told a reporter. "She said, 'I think I dropped him off.'"

Murphy, who was driving, said, "I asked her to verify what (Chauvin) was asking her - which was, was there anyone in the car," he said. "I saw the headlights out of the water, and kind of freaked out. She said each time, 'I don't think so. I think I dropped him off.'"

In her deposition, Paszek referred to this claim as a lie.

In answer to a question, she said she took a polygraph test arranged by her lawyer, Michael S. Horwatt of Reston.

Horwatt said yesterday the test, which she passed, focused on her account of the accident. He said he could not recall if she had been specifically interrogated during the test about her claim that she felt a thump and a pull to the right.

The lawyer who sued Paszek, Leonard A. Orman of Baltimore, said yesterday, "I was impressed by her. She seemed to be credible."