In the stories “The Murders in the Rue Morgue” and “The Purloined Letter,” Poe creates the genre of detective fiction and the original expert sleuth, C. Auguste Dupin. In both “The Murders in the Rue Morgue” and “The Purloined Letter,” Dupin works outside conventional police methods, and he uses his distance from traditional law enforcement to explore new ways of solving crimes. He continually argues that the Paris police exhibit stale and unoriginal methods of analysis. He says that the police are easily distracted by the specific facts of the crime and are unable to provide an objective standpoint from which to investigate. In “The Murders in the Rue Morgue,” the police cannot move beyond the gruesome nature of the double homicide. Because they are so distracted by the mutilated and choked victims, they do not closely inspect the windows of the apartment, which reveal a point of entry and escape. Dupin distances himself from the emotional aspect of the scene’s violence. Like a mathematician, he views the crime scene as a site of calculation, and he considers the moves of the murderer as though pitted against him in a chess game.
In “The Purloined Letter,” Dupin solves the theft of the letter by putting himself at risk politically. Whereas the Paris police tread lightly around the actions of Minister D——, an important government official, Dupin ignores politics just as he ignores emotion in the gruesome murders of the Rue Morgue. In this story, Dupin reveals his capacity for revenge. When the Minister insulted him in Vienna years before the crime presently in question, Dupin promised to repay the slight. This story demonstrates that Dupin’s brilliance is not always dispassionately mathematical. He cunningly analyzes the external facts of the crime, but he is also motivated by his hunger for revenge. Dupin must function as an independent detective because his mode of investigation thrives on intuition and personal cunning, which cannot be institutionalized in a traditional police force.