A cocky Wayne B. Williams blamed some victims of a string of murders in Atlanta, and their parents, for the slayings, according to a tape recording introduced today as evidence against him.

"I work with kids a lot and some of these kids run around at all hours of the night in places they have no business of being in," he said in a tape recording of an extraordinary press conference he had at his parents' home last June 4, after police had questioned him in the slayings. "I feel some of these parents need to tighten up."

It was the first glimpse the jury has been given of the cool, arrogant side of Williams. The 23-year-old defendant is accused of killing Nathaniel Cater, 27, and Jimmy Ray Payne, 21, two of the 28 murder victims. It also shored up FBI testimony detailing the many holes in the story he told police about his predawn outing May 22, 1981, on the Jackson Parkway Bridge. He was stopped after police on stakeout heard a splash in the Chattahoochee River.

Two days later, Cater's body washed up 1.2 miles downstream, near the spot where Payne's body was found a month earlier.

The tape recording portrayed a brash suspect who seemed to relish in his inquisition by police. The press conference came after the FBI had grilled him about the slayings for 11 hours and then set him free. Williams bragged to reporters about a wreck he engineered between undercover police tailing him and said he had dared FBI inquisitors to arrest him if they had the evidence.

"I said, 'If you saw someone throwing something off the bridge, I would have arrested that person on the spot,' " said Williams in a calm voice. "I told them, 'If you have the evidence, arrest me or let me get the heck out of here.' "

He signed a waiver of his Miranda rights because he had "nothing to hide," he said, then agents pressed him to confess. "They openly said, 'You killed Nathaniel Cater and you're lying.' One said, 'It really looks bad. We've got all this evidence. Why don't you just admit to all these 20-odd murders?' "

But Williams denied having anything to do with the murders. Police have said he was cooperative, even seeming to enjoy the 11-hour grilling. "At the end of the evening, he had to be told to leave," FBI agent William McGrath testified today.

On tape, Williams prided himself in hanging tough. A "normal" person might have been browbeaten into confessing, he said as the tape whirred and jurors hunched forward to listen in the courtroom. "A normal person would have been crying or in a mental hospital. I cried a bunch of times at FBI headquarters . But I'm a hell-raiser, a rebel by nature. I'll question anything."

In a second interview with police, Williams substantially altered his account of events from what he told police the night he was first stopped for questioning, according to McGrath, an FBI supervisor. He said agents interviewed Williams on June 3 to try to clear up discrepancies in what he told police earlier. But he said that Williams contradicted himself further in that interview.