By the end of 1678, Bosse attended a party held by her friend Marie Vigoreaux, the wife of a dressmaker, in the Rue Courtauvilain.
During the party, she became drunk and boasted freely that she had become so wealthy by selling deadly poisons to members of the aristocracy that she would soon be able to retire.
On the morning 4 January 1679, Marie Bosse was arrested with her daughter Manon and her sons, François and Guillaume.
Their confessions revealed that the illegal sale of poison in the capital was handled by a network of fortune tellers.
Marie Bosse confessed to having provided the poison used by Marguerite de Poulaillon in her attempted murder of her husband.