Herman Mudgett, better known as H. H. Holmes, was an American serial killer, con artist, and bigamist in the 19th century. He confessed to 27 murders, but is commonly said to have killed as many as 200 people. 

A graduate of the University of Michigan’s medical school, Dr. H.H. Holmes moved to Chicago to pursue a career in pharmaceuticals. While in Chicago during the summer of 1886, Holmes came across Dr. E.S. Holton’s drugstore at the corner of S. Wallace and W. 63rd Street, in the neighborhood of Englewood.  Holton was suffering from cancer while his wife minded the store. Through his charm, Holmes got a job there and then manipulated her into selling him the store. They agreed she could still live in the upstairs apartment even after Holton died. Once Holton died, Mrs. Holton mysteriously disappeared and Holmes told people she was visiting relatives in California. As people started asking questions about her return, he told them she enjoyed California so much that she decided to live there.

Holmes purchased a lot across from the drugstore, where he built his three-story, block-long “Castle"—as it was dubbed by those in the neighborhood. It was opened as a hotel for the World’s Columbian Exposition in 1893, with part of the structure used as commercial space. The ground floor of the Castle contained Holmes’s own relocated drugstore and various shops, while the upper two floors contained his personal office and a maze of over one hundred windowless rooms with doorways opening to brick walls, oddly angled hallways, stairways to nowhere, doors openable only from the outside, and a host of other strange and labyrinthine constructions. Holmes repeatedly changed builders during the construction of the Castle so only he fully understood the design of the house, thus decreasing the chance of being reported to the police.

After the completion of the hotel, Holmes selected mostly female victims from among his employees (many of whom were required as a condition of employment to take out life insurance policies for which Holmes would pay the premiums but also be the beneficiary), lovers and hotel guests, torturing and killing them. Some were locked in soundproof bedrooms fitted with gas lines that let him asphyxiate them at any time. Some victims were locked in a huge soundproof bank vault near his office where they were left to suffocate. The victims’ bodies were dropped by secret chute to the basement, where some were meticulously dissected, stripped of flesh, crafted into skeleton models, and then sold to medical schools. Holmes also cremated some of the bodies or placed them in lime pits for destruction. Holmes had two giant furnaces as well as pits of acid, bottles of various poisons, and even a stretching rack. Through the connections he had gained in medical school, he sold skeletons and organs with little difficulty. 

Following the World’s Fair, with creditors closing in and the economy in a general slump, Holmes left Chicago. He reappeared in Fort Worth, Texas, where he had inherited property from two railroad heiress sisters, to one of whom he had promised marriage and both of whom he murdered. There he sought to construct another castle along the lines of his Chicago operation. However, he soon abandoned this project, finding the law enforcement climate in Texas inhospitable. In July 1894, Holmes was arrested and briefly incarcerated for the first time, for a horse swindle that ended in St. Louis. He was promptly bailed out, but while in jail, he struck up a conversation with a convicted train robber named Marion Hedgepeth, who put him in touch with a con-artist associate named Benjamin Pitezel.

Holmes and Pitezel concocted a plan to bilk an insurance company out of $10,000 by taking out a policy on Pitezel and then faking his death. The scheme, which was to take place in Philadelphia, was that Pitezel should set himself up as an inventor, under the name B. F. Perry, and then be killed and disfigured in a lab explosion. Holmes was to find an appropriate cadaver to play the role of Pitezel. Holmes then killed Pitezel. Forensic evidence presented at Holmes’s later trial showed that chloroform was administered after Pitezel’s death, presumably to fake suicide.

Holmes proceeded to collect on the policy on the basis of the genuine Pitezel corpse. He then went on to manipulate Pitezel’s wife into allowing three of her five children (Alice, Nellie and Howard) to stay in his custody. He traveled with the children through the northern United States and into Canada, eventually killing all three of them.

In 1894, the police were tipped off by his former cellmate, Marion Hedgepeth, whom Holmes had neglected to pay off as promised for his help setting up the insurance scheme. Holmes’s murder spree finally ended when he was arrested in Boston on November 17, 1894, after being tracked there from Philadelphia. He was held on an outstanding warrant for horse theft in Texas, as the authorities had little more than suspicions at this point and Holmes appeared poised to flee the country, in the company of his unsuspecting third wife. After the custodian for the Castle informed police that he was never allowed to clean the upper floors, police began a thorough investigation over the course of the next month, uncovering Holmes’ efficient methods of committing murders and then disposing of the corpses.

The number of his victims has been estimated to be between 100 and 200, based upon missing persons reports of the time as well as the testimony of Holmes’s neighbors who reported seeing him accompany unidentified young women into his hotel—young women whom they never saw exit. The discrepancy in numbers can perhaps best be attributed to the fact that a great many people came to Chicago to see the World’s Fair but, for one reason or another, never returned home.  

H. H. Holmes was executed on May 7, 1896, nine days before his 35th birthday.