Attorneys for Wayne B. Williams rested their case today, moments after the accused killer labeled the prosecutor a "fool."

Williams, on the stand for the third day in his trial on charges of murdering two young black Atlantans, revealed an arrogant side to the polite self-portrait he has painted on the stand until now.

"Isn't it true that this was your center stage, your greatest challenge, a contest between you and the police?" needled Jack Mallard, the assistant Fulton County district attorney.

"You must be a fool," said Williams, a self-styled music promoter who is charged with killing Nathaniel Cater, 27, and Jimmy Ray Payne, 21, two of the 28 young blacks whose murders have been under investigation for two years by a special police task force.

Mallard, 47, shot accusatory, rapid-fire questions at the defendant, finally cracking a cool persona after two days of intense cross-examination.

For the first time since Williams took the stand Monday in the ninth week of his trial, the jury glimpsed a temper prosecutors say made him capable of strangling Cater and Payne and tossing their bodies in the Chattahoochee River.

Prosecutors have been allowed to introduce evidence from 10 other murders to show "pattern, scheme and bent of mind."

Police on stakeout duty beneath the Jackson Parkway Bridge heard a splash early May 22 and pulled Williams over for questioning after he drove slowly across the bridge. Williams claims that he was driving 30 mph. He labeled a police recruit who said his speed was 3 to 4 mph a liar.

"That's something he added after he got in court ," Williams said today. "That's something you put in his mouth. You had all this time to program him."

Mallard asked if Williams had "done any programming" since he was grilled by FBI agents last June. "No," he replied. "You wanted the real Wayne Williams and you got him right here."

The prosecutor pushed him, demanding to know why the recruit would lie. "Nobody saw me do anything," Williams shot back. "Nobody saw me kill anybody."

Williams dismissed as liars eyewitnesses who placed him with several victims, including a day laborer who testified that he saw Williams and Cater holding hands downtown six hours before police say he was thrown in the river. Williams was asked why that man, a reluctant witness only discovered by investigators in mid-trial, would lie.

"With the reward as high as it is, I'd probably get out and lie about it, too," he said.

Mallard accused Williams of dumping his victims in rivers to wash off evidence after newspapers published accounts of fibers found on several bodies. Prosecution fiber experts say hundreds of fibers found on at least 11 victims match fibers from Williams' car, green carpet, bedspread and blanket. Experts also matched dog hairs from the victims with William's German shepherd, Sheba.

Williams denied the allegation, then described how he hunched over a microscope at home and performed his own analysis. He squinted at dog hairs from Sheba alongside hairs from a neighbor's dog. "I couldn't tell no difference," he declared.

Williams' performance was damaging for the defense, which was dealt other serious blows by rebuttal witnesses such as Floyd Fowler, a newsstand clerk who testified that Williams purchased karate magazines and others featuring male nudes. Fowler bolstered the prosecution's portrayal of Williams as a homosexual who used choke holds to strangle his victims.

The prosecution also cast doubt on the credibility of Williams' father, Homer, and shored up its fiber case with testimony from a carpet salesman who said he witnessed the signing of a loan agreement by the Williams family in 1971.

In that year, FBI fiber experts say, the green, wall-to-wall carpet in the house was manufactured. Homer Williams, a retired schoolteacher, claimed earlier that he had bought the family carpet in 1968.

Williams has testified that he knew Atlanta streets well as a free-lance television cameraman but had no idea how to find the South River, where several victims' bodies were found.

Today, a surprise witness, a Delta Air Lines employe, testified that he saw Williams on a bridge over the South River last March 2, several days before the body of Curtis Walker, 13, was pulled from the water. "He was just standing on the bridge, looking into the water," Vincent Giovannelli said.

Others also chipped away at the defendant's story. Angelo Fuster, who was a press secretary to former Atlanta mayor Maynard Jackson and went to FBI headquarters when Williams was questioned June 4, testified that Williams' father told him Wayne said he had stopped to throw "trash" off the bridge May 22. Williams has denied stopping there or throwing anything.

More rebuttal testimony is expected Thursday, and the case could reach the jury as early as Friday afternoon.

Mallard strode to the witness stand, smacking a slapjack in his hand. Police had found what prosecutors have described as a possible murder weapon in the ceiling of Williams' bedroom. "You used it a couple of times to slap someone upside the head?" he asked.

"You know I didn't do anything like that," Williams said.

Citing an interview Williams gave to Us magazine last year, Mallard portrayed Williams as an publicity-hungry psychopath. But Williams insisted that his attorney, Mary Welcome, instructed him to grant the interview to raise money for the defense team.

"You've got a profile of a killer, and you think I fit part of that profile," Williams said. "I may fit one part, but so do a lot of people. Why don't you go pick on them?"