LOS ANGELES, JAN. 18 -- The nation's longest and costliest criminal trial ended today with 52 not-guilty verdicts for former McMartin Pre-School teachers Raymond Buckey and his mother, Peggy McMartin Buckey, charged with molesting 11 children in a case that began with an accusation by one troubled mother in 1983.

The jury of eight men and four women deadlocked on 12 sex-abuse counts against Raymond Buckey and one of conspiracy against him and his mother. Superior Court Judge William Pounders, who said the case "poisoned everyone who had contact with it," declared a mistrial on those counts involving Raymond Buckey and dismissed the conspiracy charge against his mother.

Upset parents of several child witnesses said they will not put themselves through the ordeal of a new trial.

Experts said failure of several devices to elicit credible testimony from child witnesses in the case is likely to affect the way child-molestation cases are prosecuted nationwide.

Originally filed in 1984 as a case against seven McMartin staff members with potentially hundreds of victims, the case drew national headlines and produced widespread concern about the safety of children in private preschool classes.

One prosecutor subsequently quit amid a flurry of charges about coaching child witnesses and of doubts about the credibility of Judy Johnson, who filed the initial complaint and died from complications of alcoholism in 1986.

Buckey, 31, who spent nearly five years in jail awaiting trial, reacted to the verdict with a few short nods while female relatives in court wept in happiness.

His mother, 63, jailed almost two years, cried as the verdicts were read. "I've gone through hell, and now we've lost everything," she told the Associated Press outside court. "My concern was for my son and what they've done to him . . . because my son would never harm a child."

In an adjourning courtroom, several alleged victims, many now teenagers, sat stunned for several moments as they watched the verdict on closed-circuit television, then broke into tears. One teenager buried his face in his hands, and a girl asked a reporter, "You mean he was innocent on everything?"

Pounders has said he lived in fear of a mistrial on all charges as all six of his alternate jurors moved onto the panel due to illness and mishap during the 33-month trial that cost about $15 million.

Today, he thanked the panel and said, "No jury has had to endure what you have had to endure." He scheduled a hearing Jan. 31 to consider motions for a new trial on the 13 deadlocked counts against Raymond Buckey.

Several jurors, meeting with reporters at Pounders's urging, said they believed that some children had been molested but could not determine from the evidence whether the Buckeys were responsible.

They were particularly critical of videotaped initial questioning at Children's Institute International (CII), a child-abuse clinic, which indicated that counselors raised the possibility of molestation by the Buckeys before the children did.

Nine of the 11 allegedly molested children repeated their stories at the trial, but juror Brenda Williams, 38, a telephone-company service representative, said, "If we had not seen those tapes, I would have been able to believe their testimony a little more."

Extensive medical evidence, often absent in molestation cases, appeared to have no effect on the jurors.

Astrid Heger, director of the child sexual-abuse program at Los Angeles County-USC Medical Center, testified that she was surprised to see visible scarring in so many children tended by the Buckeys.

But juror John Brees, 51, a biomedical-equipment technician, said the significance of the evidence faded in his mind "after hearing all the conflicting medical experts discuss this for months, literally months."

Brees, who has eight children, complained that jurors were deluged with testimony from adult experts and testimony elicited from children, usually in a very few words or sentences, by adult counselors and attorneys.

"The children were never allowed to say in their own words what happened to them, and to me that was crucial," he said. "They never had a chance to tell their story."

Throughout the trial, prosecutors and child-abuse counselors contended that small children could not be expected to recall such traumatic incidents without help, particularly when Raymond Buckey allegedly had threatened to hurt their parents or them if they told. One alleged victim was only 2 years old at the time.

Juror Sally Cordova criticized a letter sent to parents by police in Manhattan Beach, the Los Angeles suburb where the school was located, revealing the molestation accusations before charges were filed. "The police letter should have never been sent," she said.

Deputy District Attorney Lael Rubin, the chief prosecutor, said today of the Buckeys: "The system worked well for them. They were lucky. I hope we never hear anything again about either of them molesting children."

The mother of one of the children whose alleged molestation produced a deadlocked verdict cried softly and said, "I can't believe that they couldn't find him guilty of at least one count. All the children's stories were the same."

She said that her daughter "would do okay" but that neither would participate in further trials.

A former criminal attorney, who decided not to subject his daughter to the ordeal of testimony despite her story of being molested by Raymond Buckey, called the verdict "disappointing but understandable."

He said that prosecutors would be more careful in initial interviews of potential witnesses and that CII counselors remain "heroes to the parents, because they weren't trying to build evidence for a case but find out what happened so the kids could be treated."

The Associated Press quoted Mary May Cioffi, a parent vocal about the case although her children did not testify, as saying "the anger is beginning to rise. We have programs all over the country that tell children to run and tell when somebody hurts them, and our children told. Some of them spent 35 days on the stand, and they get a 'not guilty.' "

District Attorney Ira Reiner, who before the trial ordered charges against the other five defendants dropped for insufficient evidence, noted that, during the McMartin case, "our office filed 1,600 to 2,000 other molestation cases, and our conviction rate exceeds 90 percent."

Some McMartin defendants are reportedly planning to sue Los Angeles County and some news organizations, claiming they were harmed by prosecution and publicity about the case.

Reiner said he plans to recommend that judges be empowered to limit testimony in future cases so trials will not last so long.