The case dragged on for seven years, involved testimony from hundreds of witnesses, charged seven defendants on hundreds of counts, received massive media attention and cost $15 million, yet in the end, there wasn't a single conviction.
It was the McMartin preschool trial, and it focused on accusations of sexual abuse against the children in the school's care.
In 1983, Judy Johnson, the mother of a student at the school, made an allegation of sexual abuse against Ray Buckey, a teacher at the school and grandson of its founder. Under normal circumstances, the police would have investigated this allegation and prosecutors would have decided whether to pursue charges against Buckey. As you might have guessed, though, this was no normal case.
The police did question Buckey but charges were not pursued due to lack of evidence. However, the police then sent a form letter to 200 parents of students at the school detailing disturbing allegations against Buckey and asking the parents to question their children.
Ultimately, several hundred children were interviewed as part of the investigation, and the interview techniques soon came under fire for being highly suggestive and creating false accusations. According to Michael Maloney, a psychiatry professor knowledgeable about the interviewing of children, the techniques used were coercive and directive to the point where "many of the kids' statements in the interviews were generated by the examiner."
Some of the allegations were truly bizarre, as children claimed to have participated in grotesque Satanic rituals, dug up dead bodies, traveled to space in a hot air balloon or seen witches flying. One witness even claimed that popular actor Chuck Norris had been present at some of the rituals.
In hindsight, it appears that virtually all of the testimony was the result of mishandling by the adult investigators. For example, one of the allegations was that children were photographed nude as part of a game called "naked movie star." It turns out that the origin of this idea was a harmless rhyming taunt the children used to tease each other: "What you say is what you are, you're a naked movie star."
In the end, after seven years, all seven defendants were acquitted or had their charges dismissed. The McMartin preschool trial stands today as a grotesque example of what can go wrong and how badly justice can be miscarried as the result of inappropriate investigation and trial techniques.