At around the age of twenty, Béatrice was married to Bérenger de Roquefort, the châtelain of the small and largely Cathar community of Montaillou.
Béatrice was not in love with her husband, an entirely normal state of affairs as noble women usually married for economic reasons.
This relationship lasted two years before Béatrice decided to leave the mountain village and marry another minor noble, Otho de Lagleize.
The charge of witchcraft was supported by the contents of her purse, which included a variety of "objects, strongly suggestive of having been used by her to cast evil spells": two umbilical cords of her grandsons, which ensured victory in any lawsuit; linens soaked with her daughter's first menstrual blood, meant to be drunk by the daughter's husband to ensure his love; frankincense to cure bad headaches; some of the herb rocket, Eruca sativa, thought to enhance sperm quality and sexual vigor, which Beatrice refrained from telling Fournier was meant for her husband, the priest; a mirror and a small knife wrapped in a piece of linen; the seed of the herb ive, wrapped in muslin, as a remedy for epilepsy for her grandson; a dry piece of bread called "tinhol" (possibly millet bread); written formulas; and numerous morsels of linen.
Indeed, Rene Weis comments that Fournier would have recognized the contents as innocuous charms and love potions, except for the bread, which indicated Cathar interests.
The band Supreme Fiction has a song on their album Quivering Things about Béatrice titled "Beatrice of Montaillou Recants Her Repentance."