The First Detective: The Life and Revolutionary Times of Vidoq Criminal, Spy, and Private Eye by James Morton.

Before Sir Robert Peel proposed the Metropolitan Police Act, before the New York City Police Department was founded, before Alan Pinkerton set up his famous detective agency there was Eugène François Vidocq.
Born in relative obscurity, this son of a baker from Arras would come to have a wild and storied career, on both sides of the law. Soldier, criminal, police informant, policeman, private detective, master of disguise, spy, patron of the arts, and man of letters Vidocq was the founder, and first chief, of the Brigade de la Sûreté (Brigade of Safety) a revolutionary plain clothes police force that would eventually become France’s National Police Force. After his resignation from the Brigade de la Sûreté (Vidocq also made enemies on both sides of the law) he established the world’s first private detective agency. His exploits and character were so well-known that he served as the inspiration for several literary characters (including Victor Hugo’s Jean Valjean and Inspector Javert), Vidocq was very famous (Or infamous depending on who you asked).
James Morton provides an entertaining and educational look into the life of a revolutionary character who was truely famous (or infamous depending on who you asked).