It was at about 2:30 a.m. yesterday that 22-year-old John W. Lauler III turned away from a weedy lot on Lowell Avenue in McLean, where he had been standing in a noisy corner of a large beer party, and wandered off down the street.

His friends never knew where he was going. It was not until much later, after the ambulance had been parked across Lowell Avenue and the police had come to take the names and license tag numbers of partygoers that they realized he was lying only one block away, apparently struck and killed by a passing car.

"We were just sitting there, drinking," said one friend yesterday. "And all of a sudden, everybody said, 'Where's Lauler?'" His friends said yesterday they thought Lauler had headed home, or to a restaurant on the corner.

Fairfax County police said Lauler was found lying face down in the middle of Lowell Avenue, about 300 yards west of the party. He had been killed, police said later, by a massive blow to his head. A tire track was imprinted on his arm.

Police said yesterday that Lauler had apparently been killed by a hit-and-run driver. And both his friends and the other young men who had thrown the party grimly speculated that Lauler could very well have been killed by one of the dozens of drunken revelers who were speeding to and from the lot along the narrow, tree-shaded street Saturday night.

"It could easily have been somebody at the party," said one youth, who said he had helped put on the keg party, one of several that have been held in the vacant lot.

"In fact," said the youth, "I think somebody will probably turn themselves in for it. Everybody was tearing up that street."

That youth and a friend who had helped sponsor the party said more than 100 people and dozens of cars had filled the lot during the night.

Police were called to the scene shortly after 3 a.m. by neighbors complaining about the noise. An officer driving down Lowell Street to the party discovered the body, police said.

Investigator Colin Kozloff said yesterday there were no suspects. "We have no reason to believe it was anything but hit and run," Kozloff said.

For the past 1 1/2 years, friends said, Lauler had lived with four other men in a secluded two-story house at 1508 Emerson Ave.

Together with one housemate, Rick Quinn, Lauler recently had bought an interest in the Westlawn Citgo Service Center at 3040 Annandale Rd. in Falls Church, and Lauler was working there as a mechanic, friends said.

According to John W. Lauler Jr., his son had lived away from the family home at 972 Saigon Rd. in McLean since graduating from Marshall High School in 1974.