An intelligent, cold and calculating doctor was America's first serial killer. There were no doubt others that came before him (such as Jack the Ripper across the pond), but none were publicized in the press and popularized like Herman Mudgett, aka H.H. Holmes. In his childhood he showed the typical malicious behavior and cruelty often associated with someone who would likely go on to murder multiple people. And murder them he did.
His crimes were so heinous that even a comic book (SURE-FIRE COMICS, June 1940) told of one of the events in this human monster's "career". The article following is from the magazine MURDER MOST FOUL (April 2018).