Wayne B. Williams declared his innocence today in a calm, clear voice, telling the jury, "I haven't killed nobody. I haven't thought about it, and I don't plan to think about it, or do it to nobody."

Hands clasped in his lap, Williams said he had never met either of the two men he is accused of killing, contradicting two eyewitnesses who placed him with Nathaniel Cater, 27, and Jimmy Ray Payne, 21. The two are among 28 young black Atlantans whose murders are being investigated by the FBI and a police task force.

Williams also denied knowing any of the 10 other victims the prosecution has been allowed to introduce in an effort to prove "pattern or bent of mind."

Speaking softly, Williams portrayed himself as a hard-working talent scout who sought to catapult ghetto youngsters to stardom in the cut-throat music world, while harvesting his own bushel of money and fame along the way.

He labeled a young black who testified that Williams had fondled him "a bald-faced liar," the same words he used to describe police officers who stopped him near the Jackson Parkway Bridge in the predawn darkness May 22.

That morning, police heard a splash in the Chattahoochee River. According to police testimony, Williams was stopped because his car drove slowly across the bridge immediately after the splash. Two days later, Cater's nude body washed up downstream, near the spot where Payne was found a month earlier.

Prosecutors say Williams cruised the streets in various cars, using his jobs as a free-lance television cameraman and self-styled talent scout as a cover to pick up young blacks and kill them in ways that left few marks and little evidence, save for hundreds of fibers prosecution experts have used to try linking him to 11 of the 28 blacks murdered here over two years.

Williams was enraged about poor street children and was driven to purify his own race by killing them, prosecutors say. But Williams said he grew up with poor blacks in the Dixie Hills section of Atlanta and wanted to help some of them sing their way out of the ghetto.

"I have nothing whatsoever against poor people," he said. "I consider myself poor. I didn't have enough money to hire lawyers for this trial. If that isn't poor, I don't know what is. I don't have no grudge against nobody."

Several witnesses have said Williams spoke disparagingly of his own race. But the defendant explained that he only used the word "nigger" in jest with other blacks and would "take offense" if a white used it in addressing him.

He denied any homosexual tendencies. "I don't have no grudge against them, just as long as they keep their hands off me," he declared.

Williams' attorney, Alvin Binder, led the 23-year-old defendant in recounting his life as the precocious only child of two retired schoolteachers. Williams was an effective witness in his own defense, confessing to "hyping" his resume to get ahead and showing evidence of a sense of humor.

The courtroom fell silent, and spectators hunched forward in their chairs as Williams took the stand for the first time as the trial entered its ninth, and possibly, final week. His testimony is to continue Tuesday when he also is expected to face tough cross-examination.

Williams had no complaints about his jail treatment but drew the line at praising the cuisine. Asked how he liked the food, he replied, "I'm under oath," bringing laughs from the jury.

He exuded a quiet confidence and was articulate on the stand. He said he believed he had been a modest success in the music business, even though he had never cut a record and spent more than $20,000 of his parents' money to assemble a group of youngsters he hoped would rival the Jackson Five.

He said he sought youngsters who looked alike "because looks are important in the music business." Several youngsters auditioned by Williams have testified that he asked personal questions about their sex lives and use of drugs. He denied any impropriety.

As for drugs, he said, "I didn't want them smoking dope all the time. But there's a big difference between smoking one reefer and others who smoked eight or nine a day. We wanted to make sure they had something going for themselves."

Binder marched his client to the jury box and asked jurors to feel his hands for callouses, trying to scuttle prosecution charges that Williams practiced karate. Jurors seemed to recoil, though three reached out to feel Williams' palms.

Later, the Williams' feeble German shepherd, Sheba, was paraded about the courtroom on a leash. One witness who saw Williams with Cater said there was a "frisky" German shepherd nearby. Today, Sheba limped.

Earlier in the day, Williams' defense suffered a serious blow when his mother, Faye, contradicted herself about previous testimony.

She told the grand jury last July that Wayne had left the house at 1 a.m. May 22 to find an aspiring singer whose telephone number had been bogus. That singer, Cheryl Johnson, has never been found. Today, she said Wayne told her he had spoken with the woman on the phone.

She also stumbled on the dates that a green, wall-to-wall carpet was installed in her home. Prosecutors have staked a large portion of their fiber evidence to their claim that the carpet was manufactured in 1971.

Faye Williams claimed it was bought in 1968, but loan documents introduced by prosecutors suggest it may have been purchased in 1971.