The case began with an abandoned car at a Fairfax wrecking yard. It ended with an arrest, 1,500 miles away, of a man accused of sexually assaulting a young child.

The car, found by Virginia State Police along Interstate 95, was about to be demolished last month when an employee searched it for valuables. Finding the tape, the employee took it home and saw scenes of a man involved in sexual acts with a 6-year-old girl, police said.

On Tuesday, after police investigators in two states and the District traced him through a chain of clues left by the tape, William Boyd McIntyre, 29, was arrested in New Boston, Tex.

McIntyre is being held in jail in Texarkana, Tex., in lieu of $50,000 bail on a charge of indecency with a child by sexual contact, a felony punishable by up to 20 years in prison and a fine of up to $20,000, said Bowie County District Attorney John Miller.

McIntyre had lived in Fairfax for at least a year and had recently worked as a maintenance man in a local retirement home before moving back to Texas, police said.

According to police, the wrecking yard employee first gave the tape to D.C. police, who later gave it to Fairfax County police after deciding the incidents probably did not occur in the District.

Fairfax police traced the car in which the tape was found, and contacted New Boston Police Chief Kerry Pinkham when they determined that its owner, McIntyre, had formerly lived there, Pinkham said.

Pinkham, who knew McIntyre for several years, said he believed he recognized the man in the tape.

In addition, the name of the child's mother was written on the outside of the tape, Miller said.

After interviewing the child's mother, who was not aware of the 1987 incident, and other New Boston residents, McIntyre was arrested. He originally refused to discuss the incident with police, then "he did give us a statement after viewing the tape," Miller said. "He said he couldn't explain why it had happened. He said it was the only time and that it was him."

Bowie County Sheriff's Department Detective James Prince said McIntyre said the molestation "gave him sexual gratification. He said it made him feel good."

Social workers who have interviewed the child, now 9, have determined that she probably does not remember the incident, which occurred in December 1987, Prince said. None of the acts involved sexual intercourse with the child and one scene depicted McIntyre molesting the child when she was asleep, he said.

Fairfax County police spokesman Boyd Thompson said he was unsure whether McIntyre would be charged with any offense locally. According to Virginia law, it is illegal to possess photographic materials depicting nude children, he said.

Prince said the acts on the 30-minute videotape occurred at the child's mother's house while McIntyre baby-sat for the child and another little girl. In the tape, McIntyre can be seen making faces into the camera. The videotape begins with a scene of the children playing with the woman, who later left the house. Police believe the molestation occurred after she left. The incident was never reported.

"I believe her {the mother} from her reaction that she had absolutely no idea that anything like this had happened," Prince said. "There had been nothing in the child's behavior to indicate she had been molested."

Texas police said McIntyre has no prior record of sexual offenses. He had returned to New Boston from Fairfax County about two weeks ago to help care for the 72-year-old man who had reared him, after the man became seriously ill, Pinkham said.

McIntyre "seemed like a hard-working man," Prince said. "He doesn't seem like the kind of person to do something like this."