She became mother superior of the convent at a young age, but is chiefly remembered as a central figure in the case of the possessed of Loudun in 1632, which led, after witch trials, to the burning at the stake of the priest Urbain Grandier two years later.

Jeanne was sexually fascinated with him, writing in her autobiography, "When I did not see him, I burned with love for him and when he presented himself to me […] I lacked the faith to combat the impure thoughts and movements that I felt.

[1] Then in 1632, Sister Jeanne stated that Grandier's spectral image had appeared to her, seduced her and taken from her "that which she had vowed to keep for her heavenly husband Jesus Christ.

"[2] About the same time, other sisters began to complain of disturbed nights, and of seeing ghostly men, including Moussault and Grandier, moving about the building.

Despite Sister Jeanne and the nuns withdrawing their complaint, Grandier was convicted, tortured and put to death by burning at the stake.