The King burned with indignation at the insult offered to his mistress, and was still more alarmed to find the new mysterious death creeping into the corridors of his palace. He hastily constituted the terrible Chambre Ardente, a court of supreme criminal jurisdiction, and commissioned it to search out, try, and burn, without appeal, all poisoners and secret assassins in the kingdom.
La Regnie, a man of Rhadamanthean justice, as hard of heart as he was subtle and suspicious, was long baffled, and to his unutterable rage, set at naught by the indefatigable poisoners who kept all France awake on its pillows.
History records how Gaudin de St. Croix, the disciple of Exili, while working in his secret laboratory at the sublimation of the deadly poison, accidentally dropped the mask of glass which protected his face. He inhaled the noxious fumes and fell dead by the side of his crucibles. This event gave Desgrais, captain of the police of Paris, a clue to the horrors which had so long baffled his pursuit.
The correspondence of St. Croix was seized. His connection with the Marchioness de Brinvilliers and his relations with Exili were discovered. Exili was thrown a second time into the Bastile. The Marchioness was arrested, and put upon her trial before the Chambre Ardente, where, as recorded in the narrative of her confessor, Pirol, her ravishing beauty of feature, blue eyes, snow-white skin, and gentle demeanor won a strong sympathy from the fickle populace of Paris, in whose eyes her charms of person and manner pleaded hard to extenuate her unparalleled crimes.
But no power of beauty or fascination of look could move the stern La Regnie from his judgment. She was pronounced guilty of the death of her husband, and sentenced first to be tortured and then beheaded and her body burnt on the Place de Grève, a sentence which was carried out to the letter. The ashes of the fairest and most wicked dame of the Court of Lous XIV. were scattered to the four corners of the city which had been the scene of her unparalleled crimes. The arch-poisoner Exili was also tried, and condemned to be burnt. The tumbril that bore him to execution was stopped on its way by the furious rabble, and he was torn in pieces by them.
For a short time the kingdom breathed freely in fancied security; but soon the epidemic of sudden as well as lingering deaths from poison broke out again on all sides. The fatal tree of the knowledge of evil, seemingly cut down with Exili and St. Croix, had sprouted afresh, like a upas that could not be destroyed.
The poisoners became more numerous than ever. Following the track of St. Croix and La Brinvilliers, they carried on the war against humanity without relaxation. Chief of these was a reputed witch and fortune-teller named La Voisin, who had studied the infernal secret under Exili and borne a daughter to the false Italian.
With La Voisin were associated two priests, Le Sage and Le Vigoureux, who lived with her, and assisted her in her necromantic exhibitions, which were visited, believed in, and richly rewarded by some of the foremost people of the Court. These necromantic exhibitions were in reality a cover to darker crimes.
It was long the popular belief in France, that Cardinal Bonzy got from La Voisin the means of ridding himself of sundry persons who stood in the way of his ecclesiastical preferment, or to whom he had to pay pensions in his quality of Archbishop of Narbonne. The Duchesse de Bouillon and the Countess of Soissons, mother of the famous Prince Eugene, were also accused of trafficking with that terrible woman, and were banished from the kingdom in consequence, while a royal duke, François de Montmorency, was also suspected of dealings with La Voisin.
The Chambre Ardente struck right and left. Desgrais, chief of the police, by a crafty ruse, penetrated into the secret circle of La Voisin, and she, with a crowd of associates, perished in the fires of the Place de Grève. She left an ill-starred daughter, Marie Exili, to the blank charity of the streets of Paris, and the possession of many of the frightful secrets of her mother and of her terrible father.