- Sherlock Holmes on Moriarty in "The Final Problem" Professor James Moriarty was a British crime-lord and arch-nemesis of detective Sherlock Holmes . He is, according to Holmes responsible for all organized crime in London . He is the leader of a highly secretive criminal society and has many thugs in his employ. Moriarty eventually met his end in his final confrontation with Sherlock Holmes at the Reichenbach Falls in Switzerland in May 1891. He is known as "The Napoleon of the Criminal World."