3. H.H. Holmes
H.H. Holmes is another well-known serial killer that worked as a pharmacist and insurance scammer. He built a death room that he would call ”the murder castle”. This room had various killing devices and features where he would commit his premeditated murders. Between 20 and 200 people were victims of his.
During the 1893 Columbian Exposition in Chicago, he was at his most active as a serial murderer. The exposition attracted huge numbers of people to the area, and Holmes took advantage of the influx by renting rooms in his house to tourists.
The structure Holmes built had many secret chambers where he tortured and finally murdered his victims. The structure included a network of ramps and hidden passageways that allowed him to quickly retrieve the bodies of his victims from the top floors and transport them to the basement, where they were often burnt.
His end finally came when an accomplice of him gave a tip to the police after he wasn’t paid by Holmes for his services. Holmes was finally sentenced to death in 1896.