Au début du xix^e siècle, un jeune paysan normand âgé de 20 ans tue sa mère, sa sœur cadette et son plus jeune frère. Après une errance d’un mois dans les bois, il se rend à la gendarmerie. Interrogé par le juge, il avoue son crime et l’explique dans un mémoire, écrit en prison à la demande du juge, comme une façon de protéger son père qu’il voyait menacé par sa femme et poussé au suicide par elle. L’analyse de ce mémoire fait apparaître un ratage du processus d’adolescence chez Pierre Rivière, ratage qui le conduit à un enfermement narcissique fatal pour lui comme pour ses victimes.

At the beginning of the 19th century, a young farmer from Normandy, age 20, killed his mother, his younger sister and his youngest brother. After wandering for one month in the woods, he turned himself in to the police. When he was interrogated by the judge, he admitted his crime and explained it in a statement of case, written in prison at the judge’s demand, as a way of protecting his father whom he considered to be threatened by his wife and pushed by her to commit suicide. The analysis of this statement of case reveals a failure in the adolescent process of Pierre Rivière, which led him into a fatal narcissistic shutting up, both for himself and for his victims.