H. Holmes

H. H. Holmes, born Herman Webster Mudgett, was an American con artist and serial killer widely considered the first documented serial killer in the United States. He infamously constructed the 'Murder Castle' in Chicago, a building equipped with secret passages and gas chambers used to torture and kill victims, primarily during the 1893 World's Fair. Holmes confessed to 27 murders but was executed in 1896, with estimates of his total victim count ranging as high as 200.