Dr Karl Hoffmanstahl was a German surgeon renowned for his pioneering plastic surgery techniques. He used these skills to alter several men's appearances for Professor James Moriarty, among them René Heron.
Because Hoffmanstahl knew about his plot, Moriarty decided to kill him. He therefore placed a bomb inside the payment box and sent Irene Adler to deliver it to him in an auction house in London. Although Sherlock Holmes managed to intervene in time and defuse the bomb, Hoffmanstahl was killed with a poison dart by Colonel Sebastian Moran as he left the building.