Viewer discretion is advised. Some may find this content disturbing. This is a documentary I found interesting.
Herman Webster Mudgett (May 16, 1861 – May 7, 1896), better known under the name of Dr. Henry Howard Holmes or more commonly H. H. Holmes, was one of the first documented serial killers in the modern sense of the term. While he confessed to 27 murders, of which nine were confirmed, he may have killed as many as 200 people. He brought an unknown number of his victims to his World's Fair Hotel, located about 3 miles (4.8 km) west of the 1893 Chicago World's Fair. Besides being a serial killer, H. H. Holmes was also a successful con artist and a bigamist.
Jane Toppan (1857–1938), born Honora Kelley, was an American serial killer, nicknamed "Jolly Jane". She confessed to 33 murders in 1901. She is quoted as saying that her ambition was "to have killed more people — helpless people — than any other man or woman who ever lived..."
