In France uneasiness was general after the execution of the Brinvilliers and the acquittal of Pennautier. Sinister rumors prevailed that secret poisoning had become quite a trade, facilitated by the existence of carefully concealed offices, where the noxious drugs necessary could be purchased easily by heirs tired of waiting for their succession, and by husbands and wives eager to get rid of one another. Within a year suspicion was strengthened by the picking up of an anonymous letter in the confessional of the Jesuit Church of the rue St. Antoine, stating that a plot was afoot to poison both the King and the Dauphin. The police set inquiries on foot, and traced the projected crime to two persons, Louis Vanens and Robert de la Nurée, the Sieur de Bachimont.
The first of these dabbled openly in love philtres and other unavowable medicines; and he was also suspected of having poisoned the Duke of Savoy some years previously. Bachimont was one of his agents. From this first clue, the police followed the thread of their discoveries, and brought home to a number of people the charge of preparing and selling poisons, two of whom were condemned and executed. A still more important arrest was that of Catherine Deshayes, the wife of one Voisin or Monvoisin, a jeweller. From this moment the affair assumed such serious proportions that it was decided to conduct the trial with closed doors. The authorities constituted a royal tribunal to sit in private at the Arsenal, and to be known to the public as the _Chambre Ardente_ or Court of Poisons. La Reynie and another counsellor presided, and observed extreme caution, but were quite unable to keep secret the result of their proceedings. It was soon whispered through Paris that the crime of poisoning had extensive ramifications, and that many great people, some nearly related to the throne, were compromised with la Voisin. The names were openly mentioned: a Bourbon prince, the Comte de Clermont, the Duchesse de Bouillon, the Princesse de Tingry, one of the Queen's ladies in waiting, and the Marchionesse d'Alluye, who had been an intimate friend of Fouquet. The Duc de Luxembourg and others of the highest rank were consigned to the Bastile. Yet more, the Comtesse de Soissons, the proudest of Cardinal Mazarin's nieces and one of the first of the King's favorites, had, by his special grace, been warned to fly from Paris to escape imprisonment.