During his years of murder, Gilles often came close to discovery. In 1437, his family heard that he intended to sell the castle of Champtoce, in spite of the royal interdict; they hastened to seize it. Gilles was terrified; he had left the mutilated bodies of dozens of children there. He was also afraid that the castle of Machécoul would be next since the remains of many children had been thrown into a locked tower. He and his companions removed about forty dismembered bodies from Machécoul. When he regained control of Champtoce in 1438 he hastened to remove another forty or so corpses, which had apparently remained unnoticed. Meanwhile, the Duke of Brittany had imposed a huge fine on Gilles, aware that Gilles would be unable to pay. He also began an investigation into the disappearance of hundreds of children.
In July 1440, Gilles made a fatal mistake. He had sold a castle called Mer Morte to Geoffroy de Ferron, treasurer to the Duke of Brittany, Gilles’ suzerain. For some reason, Gilles decided that he was entitled to repossess the castle, which had not yet been occupied by its new owner. The keys, it seemed, were in the hands of Geoffroy’s brother, a priest called Jean de Ferron. Instead of waiting until Jean de Ferron was in his home, he led his men into the church of St Etienne de Mer Morte soon after mass, and had the priest dragged outside, where he was beaten. By entering a church and permitting violence, Gilles had committed sacrilege, a capital offence.
Gilles’ companions later revealed that, even on this expedition to recover his castle, he had been overcome by his craving for rape and murder. After leaving the church, he had halted for the night in the town of Vannes and taken lodging in a house near the bishop’s palace. One of the ex-choristers of his private chapel, André Bouchet, had brought him a ten-year-old boy. Since his present lodging was not private enough for rape and murder, the boy was taken to another house near the market, and there sodomised and decapitated; the body was thrown into the latrines of the house, where the smell was less likely to cause its discovery.
Bishop Malestroit seized this opportunity to bring Gilles to court, on charges that he had secretly been preparing since July 29. The bishop was joined by the Inquisition, which pressed for a charge of heresy and a civil trial was called for in the ducal court.
On September 13, 1440, the Bishop summoned Gilles before the court. Preliminary hearings took place on September 28, October 8, 11 and 13, and the formal trial opened on October 15. The Duke of Brittany, John V, sanctioned a concurrent trial, which started on September 17. Gilles was at first arrogant and defiant but after six sessions, on Friday, October 21, 1440, he was tortured until he promised to confess “voluntarily and freely”.
The extensive witness testimony convinced the judges that there were adequate grounds for establishing the guilt of the accused. To procure additional evidences of his alleged crimes, his servants and four alleged accomplices were also tortured. In all, 110 witnesses (including informers) were heard. After Rais admitted to the charges on 21 October, the court canceled a plan to torture him further into confessing. The transcript, which included testimony from the parents of many of the missing children as well as graphic descriptions of the murders provided by Rais’s accomplices, was said to be so lurid that the judges ordered the worst portions to be stricken from the record. In sum, Gilles was accused of being a “heretic, apostate, conjurer of demons… accused of the crime and vices against nature, sodomy, sacrilege and violation of the immunities of Holy Church.”
On the 25 October, the ecclesiastical court handed down a sentence of excommunication against Rais, followed on the same day by the secular court’s own condemnation of the accused. Forty-seven charges were levelled against Gilles, including conjuration of demons, abuse of clerical privilege, and sexual perversions against children. The invocation of spirits charge was embellished with accusations of human sacrifices. After tearfully expressing remorse for his crimes, Rais obtained rescindment of the Church’s punishment and was allowed confession, but the secular penalty remained in place.
Charged and condemned with him were his mignon Henri Griard and his page Etienne Corillaut, called Poitou.