A preliminary analysis of fibers found at the home of a man questioned here last week in connection with the slayings of 28 blacks shows strong similarities to fibers found on a least 12 of the victims, law enforcement officials say.

But Fulton County District Attorney Lewis Slaton said the lab findings alone were not sufficient evidence to arrest the man, Wayne D. Williams, 23, a free-lance television cameraman and music talent scout who has been under intense police surveillance for the past week.

United Press International reported tonight that Williams had briefly eluded authorities, possibly with the help of his father.

Police said Williams got away from his parents' home unobserved by lying on the floor of his father's car.

[Authorities relocated Williams several hours later. They said there was no indication that he had been trying to leave town.]

Atlanta Police Superintendent Lee P. Brown today declined to name Willima as an official suspect. But investigators continued to seek evidence that could either lead to Williams' arrest or rule him out as a suspect.

Since the FBI questioned Williams last week, plainclothes officers have staked out his home in northwest Atlanta where he lives with his parents, both retired teachers. Brown said the police presence on the street was designed to shield the middle-class black neighborhood, as well as Williams, from reporters.

FBI agents with a search warrant took a blanket, carpet samples and other evidence from Williams' home last week.

Police questioned Williams after the body of Nathaniel Cater, 23, was found in the Chattahoochee River three days after FBI agents saw Williams throw something off a bridge near where the body surfaced. Police said Williams told them he had thrown garbage into the river; Williams denies throwing anything from the bridge.

A source close to the investigation said green fiber samples taken from Williams' carpet, a violet fiber from the blanket and hairs from his German shepherd were "consistent" with fibers found on at least 12 victims.

"Right now, we can say that microscopically the fibers match what we've found on the victims, but they have to do several more chemical tests before we can say it's court quality evidence," the source said. "We've taken sample after sample over the last two years and out of all the thousands of samples the crime lab has looked at, we didn't see anything that matched until now."

But forensic experts on fiber evidence cautioned that such findings rarely hold up in court.

"Agatha Christie would love a piece of silk, but you can only say [about fiber evidence] that 'this fiber is entirely different than another one,' or that they have similiarities," said Dr. John Feegel, assistant Fulton County medical examiner.

"Let's say a guy has a cashmere sweater with a particular native dye in it," said Feegel, who is a forensic pathologist and a lawyer. "It's not a commercial grade or Dupont and you find this unusual fiber [on a body] and the sweater in the [suspect's] closet. Then you can ask him several more questions. But it's all circumstantial evidence. It's promising, but not conclusive."

Moreover, said Feegel, a jury must be instructed to disregard circumstantial evidence "if there is another explanation that is noncriminal."