Herman Webster Mudgett of New Hampshire, better known by the alias H.H. Holmes, was responsible for anywhere from 20 to 200 killings before he was apprehended in 1894, and is known as one of America’s first serial killers. But ... not THE first. That title -– at least on record -- belongs to the Harpes: "Big" and "Little" Harpe, who killed at least 40 men, women, and children – and likely more. Be warned, this may be the most violent episode we have yet told.