The purpose of this research was to reveal the deviant nature of the flâneur in 19th century Paris. In order to do so it was essential to first explain the typical perspective of the flâneur in Haussmanized Paris. This individual observed the city and took in the sights, motivated by a passion for curiosity and a love for Paris. Tom McDonough among others, posits that the flâneur is not simply an individual who walks the streets of Paris to observe but rather has an alternative motivation. The flâneur can take the shape of either a shady criminal stalking his prey through the streets of Paris, or alternatively a detective using his keen observation skill and understanding of people and their environment to solve mysteries. The dual nature of the flâneur is depicted in several pieces from the period. The criminal flâneur is illustrated in De Balzac’s Father Goriot in the deviant character Vautrin while, the criminal perspective is seen in Conon Doyle’s Scandal in Bohemia through the character Sherlock Holmes. The dual nature of the flâneur is also depicted in contemporary art, including Following Piece by Vito Acconci and Bernard Tchumi’s “The Park”. This research argues that the flâneur skillfully utilizes his ability to remain incognito and blend into a crowd, in conjunction with his immense knowledge of the people and city Paris as a tool for engaging in criminal and detective behaviors.