Hydra

To kill a snake, you must cut off its head. But that can't kill a hydra. Cut off a head and more grow in its place. And so, to kill a hydra you must cut out the heart. Or burn it. Sherlock Holmes, with his international reputation and homeless network, was a snake. Kill him and his body dies, too. Crime, however, was a hydra. Criminals, its heads. And Jim Moriarty, its heart.