The Poisonings Begin
Sainte Croix set himself up as a reformed gentleman. He married, took a house and began to develop a much quieter reputation as an alchemist and a scholar. However, his affair with Marie Madeleine did not end. Instead, she joined him in his laboratory where the couple was instructed in the art of poisoning by Swiss chemist and professor of Chemistry to the royal court, Christopher Glaser. Poison was quite the thing in aristocratic circles and “Glaser’s Receipt” in particular was used by impatient heirs to speed along their legacies.
So there was profit in the poisoning business for both Sainte Croix and the Marquise. Sainte Croix had the know-how and Marie Madeleine, the connections amongst her society acquaintances. It was possible for the pair to quickly- and discretely- find customers. However, they had a more immediate aim. Sainte Croix had already encouraged his mistress to separate her affairs from that of her husband to preserve what the remainder of her fortune. Now the pair began to plot to acquire the whole of the d’Aubrey fortune.
Marie Madeleine began by testing their poisons on unsuspecting victims. She primarily used the impoverished patients of Paris’s public hospitals whose untimely deaths no one would suspect. She may even have used it on her servants. Marie Madeleine’s maid, Francoise Roussel complained that she felt as though “her heart was being stabbed” after the Marquise fed her poisoned fruit. Then, in 1666, the dress rehearsals were over. Marie Madeleine’s father fell ill. By this time, Antoine d’Aubray believed he and his daughter to be reconciled. So he had no qualms about asking her to come and nurse him.
Marie Madeleine agreed and gave every appearance of being the dutiful daughter. In fact, she was patiently dosing her father with Glaser’s Receipt. Finally after 27 doses, d’Aubray senior was dead. Marie Madeleine had had her revenge for her lover’s imprisonment. Now there was just the small matter of her two brothers, Antoine junior and Francoise, who stood between her and the entire fortune. So, in 1670, Marie Madeleine installed Sainte Croix’s faithful servant Jean Hamelin, known as La Chausse as the unmarried Francoise valet. She then paid him to poison to his new master. He even doctored the food of both brothers when they dined together. By September 1670, Antoine and Francoise were dead.
Antoine’s widow Marie Therese had her suspicions but no proof, so she removed herself safely out of Marie Madeleine’s way. However, Marie Madeleine’s dark reputation was well known. The Marquise de Sevigne, a well-known society letter writer, commented on how Marie Madeleine’s husband was only alive because he carried antidotes to her poisons. However, it seems there was a line even the murderous Marquise would not cross. When she attempted to poison her daughter, she had a change of heart and saved the child. It was, however, only a matter of time before the authorities discovered the Marquise’s reputation.