Jérôme Henri Carrein was born on July 2, 1941, in Cantin, Nord, France. Despite being born into a working-class family, Carrein's life was marred by hardship. He became an alcoholic during his teenage years and was described by psychiatrists as having a "coarse personality, mentally deficient and sexually immature." At 18, he married and fathered five children. His marriage was tumultuous, marked by domestic violence, leading to a conviction and imprisonment for assaulting his wife. After contracting tuberculosis in 1972, Carrein struggled to maintain employment, eventually becoming a semi-vagrant. He resided in Arleux, living in makeshift shelters near marshlands and relying on the goodwill of locals for sustenance. ​

On October 27, 1975, in Arleux, Northern France, Carrein encountered eight-year-old Cathy Petit, the daughter of a bar owner he frequented. He persuaded Cathy to accompany him to nearby marshlands under the pretense of searching for fishing bait, sending her brother, Éric, to inform their mother. Once isolated in the swamps of Palluel, Carrein attempted to sexually assault the child. When she resisted, he strangled and drowned her. ​

Carrein was arrested the following day and confessed to the crime. He was tried before the Pas-de-Calais criminal court at Saint Omer and sentenced to death on July 12, 1976. Due to procedural issues, a retrial was held on February 1, 1977, at the criminal court in Douai, where he was again found guilty and sentenced to death. His appeal for clemency was denied by President Valéry Giscard d'Estaing in mid-June 1977. Carrein was executed by guillotine at 4:30 AM on June 23, 1977, in the courtyard of Douai prison by executioner Marcel Chevalier. He was the second-to-last person executed in France, preceding the abolition of the death penalty in 1981.