In 1887, Robert Ledru was a 35 year old Paris police detective who was considered one of France’s best, and so when the authorities in Le Havre asked for help with a mysterious case of missing sailors, Ledru was sent to lend them a hand. He arrived in the Normandy port at evening and went to bed early. When he awoke the next morning, he was surprised to discover that his shoes and socks were wet.
When he got to the Le Havre police station, he was told that the missing sailors case was now a low priority, as there had been a murder during the night at the beach of a prominent businessman by the name of Andre Monet, who was discovered face down, shot through with a bullet. The victim had not been robbed, and nothing pointed to any reason, motive, or suspect.
Ledru went to the beach to investigate the crime scene, and noticed footprints leading up to and away from the corpse. After examining them, he seemed troubled, and remarking that they looked familiar, ordered plaster casts made of the clearest footprints. When that was done, he sat right there on the beach, looking at the plaster cast footprints for hours. Finally, he got up and told the gathered gendarmes that there was no need for further investigation, as he had solved the crime: the killer was Robert Ledru, although for the life of him he had no memory of shooting the victim. However, one of the footprints had a missing big toe and matched that of Ledru’s, who was missing a big toe. There was also an empty chamber in his revolver, which was always kept fully loaded. Finally, there were the wet shoes and socks he woke to that morning. From all the preceding, Ledru concluded that he had been sleepwalking on the beach that night, when he encountered and shot the victim.
The police were skeptical at first, and Ledru’s bosses thought their star detective must be suffering some temporary crisis caused by overwork and stress that led him to imagine himself a killer. However, ballistics testing proved that the bullet recovered at the crime scene had been fired from Ledru’s revolver, so that sealed it. He was jailed for his own good, and kept under constant watch.
While in prison, the authorities gave him a revolver loaded with blanks. One night, Ledru got up and fired it at a guard, which convinced the authorities that he was, indeed, a homicidal sleepwalker. From then until his death fifty years later in 1937, Ledru was kept in a secluded farm outside Paris, watched over by doctors and armed personnel.