Helene Jegado was born at Plouhinec in Brittany in 1803 to illiterate peasants and was orphaned early. She was raised partly by an aunt who was a domestic servant, learned to cook, and spent a period in a convent, from which she stole persistently, including from blind nuns.
From 1833 she worked as a cook in houses, presbyteries and inns across Brittany, and people around her died. In one three-month period in 1833 seven people died in the household of the priest at Guern, including Jegado's own sister. She moved on, and it happened again, in Bubry, in Locmine, in Auray, in Rennes. She nursed the sick devotedly and wept at every funeral, and she said, more than once and in front of witnesses, that wherever she went people died.
She used arsenic, which was in every farmhouse in France as rat poison and which produced symptoms indistinguishable from the cholera that was moving through the region in those years. That is the reason she lasted eighteen years.
It ended in 1851 in the household of Theophile Bidard, a professor of law at Rennes. A maid, Rose Tessier, died in 1850. Another, Rosalie Sarrazin, died in July 1851, and Bidard called in doctors who refused to sign. She was arrested when she volunteered to police who had not accused her of anything that she was innocent.
She was tried at Rennes in December 1851 on three counts of murder and three of attempted murder, everything before 1841 being barred by prescription. Twenty-three deaths were laid out in the indictment as evidence of system, and estimates of the total run to thirty-six. She admitted nothing. She was convicted and guillotined at Rennes on February 26, 1852.