Marie Margnerite Daubray Brinvilliers, marchioness de, a French woman, convicted of poisoning her father, her brothers, and many others, executed at Paris, July 16, 1676. She was highly educated, and moved in the best French society. Her father was Dreux d'Au-bray, a prominent public officer of Paris. In 1651 she married the marquis de Brinvilliers. Shortly after the marriage she fell in love with one of his friends, an adventurer named Gaudin de Sainte-Croix. Her husband did not interfere, but her father caused the arrest of Gaudin, who was incarcerated in the Bastile. Having there been taught by an Italian named Exili the preparation and application of a peculiar kind of poison, he became the instructor of the marchioness, who initiated her husband into the secret. The marquis having ruined himself by extravagance, the death of his wife's family was resolved upon, that they might obtain the property. He prepared the poison, and she experimented with it upon the sick in the Paris hospital, upon her guests, and upon her chamber maid. She made eight unsuccessful attempts upon her father before causing his death. She next poisoned her two brothers, and then attempted the death of her husband, who was saved by an antidote.

Her paramour died of the effects of the poison while he was preparing it; a box was found in his house containing the poison and her love letters and other conclusive evidences of her crime, and she left Paris: Lachaussee, a servant who had assisted her in poisoning her brothers, put in a claim upon the effects of Sainte-Croix for wages due him. Being suspected, he was arrested and sentenced to death. Before his execution he made a full confession. Madame Brinvilliers, who had taken refuge in a convent at Liege, was arrested by a policeman, who gained access to her cell under the garb of a priest, and to her confidence under the character of a lover. He also secured her papers, among which one was found intended to be read after her death, in which she confessed that she had set fire to a house and poisoned her father, her brothers, one of her children, and herself. This paper was put in as evidence at the trial. On her refusing to admit its truth, she was taken to the torture room, when she confessed not only the crimes enumerated in the paper, but others which the government withheld from public knowledge. Madame de Sevigne in her letters gives a graphic account of her execution.

The poison she used was aqua to/ana.