H.H. Holmes, often called America's first serial killer, was convicted of multiple murders, though the exact number remains unknown. He operated a "Murder Castle" in Chicago during the 1893 World's Fair, where he lured victims to their deaths with traps, gas chambers, and torture devices. After his arrest in 1894, he was sentenced to death and executed in 1896. His crimes became infamous, though much of his story is shrouded in mystery, with many questioning the full extent of his killings.
