Ronald Clark O'Bryan (nicknamed The Candyman) (October 19, 1944 March 31, 1984)
was a murderer from Deer Park, Texas convicted of killing his eight-year-old son Timothy on Halloween, 1974 with cyanide-laced candy in order to claim life insurance money. He may have also distributed poisoned candy to other children in an attempt to cover up his crime. However, Elizabeth, his daughter, and none of the other children ate any of the poisoned candy...
O'Bryan was executed on March 31, 1984 by lethal injection.[2] After O'Bryan's crimes became public, Halloween safety programs were implemented in Deer Park, teaching parents methods for evaluating the safety of door-to-door treats by visual inspection.
During the execution, a crowd of college students wearing Halloween masks showed up to cheer.[3]
http://en.wikipedia.org/wiki/Timothy_O%27Bryan
It changed the way people allowed their children to go from door to door on Halloween. A few copy cats then did some other things, such as putting razor blades in apples, afterward and hospitals x-rayed bags of candy for free. Although O'Bryan's attorneys argued that setting his date of execution on Halloween was cruel and unusual punishment. Many felt it was poetic justice and he was executed on that day.
There was a much worse one that people still remember, in the area, of the John Wayne Gacy sort. The death penalty was not in force and it was reported relatives of the victims asked for him to let out on parole. In order to kill him themselves.
This guy H. H. Holmes was remarkable, really bad stuff. There was a profit motive but only of a slight nature by some serial killers in the Pacific northwest. All quite grotesque. And there is the case of Ayn Rand's hero, William Hickman, as bad as Holmes. I won't post the details, here is the link:
http://en.wikipedia.org/wiki/William_Edward_Hickman
A more complete list of details and linke, and Ayn Rand's infatuation with him, and that of her writings by Paul Ryan, Alan Greenspan, Clarence Thomas and the Teabaggers:
http://www.alternet.org/books/145819/ayn_rand%2C_hugely_popular_author_and_inspiration_to_right-wing_leaders%2C_was_a_big_admirer_of_serial_killers?page=entire