Who Was H.H. Holmes? 'Ghost Adventures' Special Investigates Infamous Serial Killer Spirit

An October Ghost Adventures miniseries "Serial Killer Spirits" will delve into the notorious haunts of some of America's most legendary serial killers. The series—which premieres October 5 on the Travel Channel and will air each Friday throughout October—will begin with the murder castle built by killer H.H. Holmes.

Holmes gained notoriety as one of America's first serial killers. Ghost Adventures investigator Billy Tolley explained the decision to kick off the series with the old school murderer in an interview with TV Insider. "There were so many victims. The heartlessness," he said. "When you have a hard time grasping someone would do something like that, and with children, no less. Cut up their bodies as if they are not even human beings. The fact we try to communicate not only with the serial killers but with the victims as well. A lot of times that happens."

The Ghost Adventures Crew will take their investigation on Holmes to Indiana, where the serial killer is believed to have claimed a number of victims, some of which, as Tolley mentioned, were children. Holmes is best known, though, for his murders of young women in Chicago during the World's Fair in 1893.

Holmes erected the three-story hotel just a few years before the fair and offered rooms to women looking for jobs, according to the Crime Museum. Every patron who stayed in his hotel was required to have a life insurance policy.

The hotel was equipped with unique and disturbing ways to kill its visitors. Holmes may be best known for his ultra-gruesome interior design. Over 100 rooms were designed with different, creepy measures. Some acted as gas chambers, while others were entirely soundproof. Peepholes and trap doors were also common in Holmes' hotel. It's also widely believed the castle had chutes in many rooms, which were used to send the bodies of Holmes' victims to the basement of the hotel.

In the basement, Holmes had an entire laboratory dedicated to dissecting and skinning his victims. Many of the skeletons were then sold as display models to medical schools. Holmes was no stranger to dissection. Before beginning his murderous rampage, he was a medical student.

It's not entirely clear if Holmes' motive was insurance fraud or simple bloodlust, though Holmes reportedly had been obsessed with skeletons and death from childhood.

The early American serial killer was eventually caught and executed by hanging. As with many historical tales, some legends claim that Holmes escaped and the wrong man died in his place, according to the History Channel.

Before his death, he confessed to 27 murders, though the actual number is likely much higher. Holmes is also the inspiration for the famous book Devil in the White City.

The infamous murder castle no longer stands. The terrifying building has been replaced by a nondescript post office, which still attracts ghost hunters and true crime fans wishing to explore the site of Holmes' heinous acts.