Born Herman Mudgett in 1860, H.H. Holmes may be America's most prolific killer. His demented behavior first surfaced as a medical student at the University of Michigan. As in his future killings, Holmes was able to profit from his crimes, taking out fictitious insurance policies and claiming the cash using corpses stolen from the school's medical labs. Eventually caught and expelled, Holmes moved on to Chicago and landed a pharmacist job where he soon swindled the business away from the widow owner.

The drugstore did well and Holmes bought an empty lot across the street, building a "castle" (pictured at left) complete with trapdoors, secret rooms, gas chambers and vats of acid. Moving the pharmacy over to the new building, Holmes also began renting out rooms and spending much time luring and seducing women in order to kill them and swipe their money. Holmes dispatched of the remains of his victims using the acid and occasionally selling the skeletons to doctors and medical teachers.

Holmes' many victims included his lover and wife of a former employee, Julia Comer, who he killed in his basement after the woman became pregnant with Holmes' child. He also disposed of Julia's young child, Pearl. Holmes murdered a fiancee, Emeline Cigrand, locking her in his vault until she suffocated. Many employees and their family members perished at his hands. Of course, not before Holmes found some way to make money from their deaths.

Holmes made a particularly huge killing, literally, during a World's Fair in Chicago in the early 1890's. Many visitors to Chicago that lodged at the castle did not return. But it was a simple fraud that forced Holmes to flee with another former employee's wife after he murdered her husband and their three children. He was eventually arrested and sentenced to die in 1895 after police had searched his ghoulish home. Before his execution on May 27, 1896, Holmes admitted to twenty-seven killings, probably a fraction of his true total.