Likely inspiration for the story

As I watched this movie, this unusual story came to mind.

I forget the date involved. It was late 1800's, I think.

Robert LeDru, a police investigator, burnt out by long hours and a gruesome work load, had a nervous breakdown and committed himself to a sanitarium. Because the place was cold and damp, he took to sleeping in his socks, which were often inexplicably wet when he awoke. His former colleagues called for his services in an unsolved murder case. The detective noted that the footprints left near the body, like his own foot, were missing a toe. He placed his own foot in the print, and to his surprise discovered that he had sleepwalked out of the sanitarium and killed the man himself.