Considered by many to be the first detective novel, The Lerouge Case (aka The Widow Lerouge) introduces Monsieur Lecoq (later Inspector Lecoq), a former “habitual criminal” who becomes a police officer. Emile Gaboriau based Lecoq at least in part on an actual criminal-turned-police-officer, Eugène Vidocq, who went on to be the first director of the Sûreté...