The surname of the two murdered women in The Murders in the Rue Morgue is L'Espanaye. Madame L'Espanaye and her daughter, Camille L'Espanaye, are found dead in their Paris home at the center of Poe's mystery.
The story was first published in Graham's Magazine in April 1841 and introduced C. Auguste Dupin, Poe's brilliant amateur investigator. The police initially arrest Adolphe Le Bon, but Dupin examines the physical evidence and notices that the crime could not have been committed by an ordinary human murderer. The locked room, extraordinary strength, and conflicting reports about a second voice all point toward a startling solution.
The killer is ultimately revealed to be an orangutan that escaped from its sailor owner while carrying a razor. L'Espanaye is therefore the family name of the victims, not the name of the detective or the wrongly accused man. Dupin later reappeared in Poe's stories The Mystery of Marie Rogêt and The Purloined Letter.