The other X-witnesses, one of whom worked for the police, told similar stories of childhood abuse, and described hunts at which children were chased through woods with Dobermans.

Mr. De Baets, the book says, became convinced that the horrors Mrs. Louf dredged up from her memory corresponded to the truth. He had each of her statements checked out, and discovered that she had inexplicably detailed knowledge of the unsolved murders of two young women in the 1980s that supported the thesis of a conspiracy.

"We tried to find out if what she said was possible," Mr. De Baets later said, "and yes, it was possible."

According to the authors, senior magistrates and gendarmerie officials became concerned about the sweeping scope that the investigation was assuming and about the enormity of the evidence. They therefore initiated an inquiry into Mr. De Baets's handling of the case, which eventually consumed as much time and energy as the investigation itself.

"The suspicion grew that De Baets and others formed part of a sect bent on destabilizing the kingdom," the book says, adding that because of this, Mr. Baets and his colleagues were dropped from the investigation and sent home on indefinite leave.

In 1997, a judge charged Mr. De Baets with concealing the fact that Mrs. Louf had incorrectly identified the photograph of a murder victim, which would have seriously undermined her evidence. In fact, the authors said, the videotape of the interrogation showed that Mrs. Louf was deeply averse to looking at the photographs. It was later established that the missing piece of evidence, known as a proces verbal, had been in the files all along.

Mr. De Baets was exonerated this year. In November, two journalists from Le Soir Illustre, who were judged to have defamed him and four colleagues, were ordered to pay the gendarmes 2.2 million Belgian francs ($55,000), plus costs. Mr. De Baets and his colleagues, however, remain on leave.

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