Besnard was born in 1896 at Saint-Pierre-de-Maille and lived at Loudun in the Vienne. Between 1927 and 1949 twelve people connected to her died, among them her first husband Auguste Antigny, her second husband Leon Besnard, his parents, her own parents, and several elderly neighbours and relatives from whom she inherited. She ended up a woman of property in a small town where most of her family had died.
Those who died were Auguste Antigny, thirty-three, her first husband; Marie Lecomte, eighty-six; Toussaint Rivet, sixty-four, and Blanche Rivet, forty-nine; her father Pierre Davaillaud, seventy-eight; her grandmother Louise Gouin, ninety-two; and her stepfather Marcellin Besnard, seventy-eight.
In 1949 a neighbour, Madame Pintou, told the police that Leon Besnard had said on his deathbed that his wife was poisoning him. Twelve bodies were exhumed and the toxicologist Georges Beroud reported arsenic in them. She was arrested in 1949 and the French press named her la bonne dame de Loudun.
Her trials, in 1952, 1954 and 1961, destroyed the case against her. Her lawyer, Albert Gautrat, and the defence experts, including the physicist Rene Truhaut, demonstrated that the exhumation and analysis had been carried out so badly that the results were worthless: the samples had been mislabelled and cross-contaminated, the cemetery soil itself contained arsenic, and Beroud's methods could not distinguish arsenic absorbed from the ground after burial from arsenic administered before death. The scientific case simply came apart in open court over the course of three hearings.
She was acquitted on December 12, 1961, having spent years in custody and eleven under accusation. She returned to Loudun and lived there until her death on February 14, 1980. She wrote a memoir maintaining her innocence and sued the state, unsuccessfully.
Nothing was ever proved against her. This roster gives her victim count as null and describes twelve as suspected, which is the correct way to carry it. She is in the archive because the case was one of the great French criminal affairs of the century, and it is remembered as a landmark in the law of forensic evidence. The trial at which soil contamination and laboratory practice were put to a jury and won. The entry should not be read as an account of murders.