Oh my, I'd never heard of Dr. Henry H. Holmes. Just looked him up and wasn't he an enterprising murderer? His "hotel" certainly was efficient. He's apparently considered the first American serial killer, although with a possibility of over 200 victims in ten years, perhaps mega-serial killer might be more appropriate. They didn't fool around back then, trial in Oct. 1895, hanging in May 1896.
There are several books about Holmes, the last one, "DEVIL IN THE WHITE CITY", by Erik Larson, is well worth reading. If you'd like a few other titles, just let me know.