The monk Ambrosio kills his mother Elvire (The Monk, t3, Favre, 1797) - Patas after Langevin

The monk Ambrosio has become debauched, trained by the devil who has taken on the appearance of Matilda. But soon jaded, Ambrosio is drawn to Antonia, in reality his own sister from whom he was separated at birth. Aided by Mathilde, who provides him with a silver myrtle capable of opening any door and putting any person to sleep, he manages to enter the house and then the bedroom of his victim, and is about to enjoy her while she sleeps, when Elvire, Antonia's mother, and therefore his own mother, intervenes. Unmasked, Ambrosio thinks only of preventing Elvire from screaming and strangles her to death.

The text of the Favre edition modifies the original text by removing supernatural events and sparing the effects of surprise: the reader is only supposed to learn at the end of the novel that Antonia was the monk's sister and Elvire his mother.