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. Émile 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. In this first book, Lecoq plays a relatively small part, the bulk of the mystery solving being done by Lecoq’s mentor Tabaret, an amateur detective.