Final answer:
The man referred to in the question is not specified, but the description matches that of Henry Lee Lucas, a notorious American serial killer convicted of multiple homicides who received the death sentence.
Step-by-step explanation:
The sadistic man referred to in the question is not specified in the provided information. However, it is important to note that the description of the man as a prolific serial killer who confessed to killing 500 people but later recanted most of his testimony matches the description of Henry Lee Lucas, a notorious American serial killer convicted of multiple homicides. Lucas was convicted of ten homicides at his 1985 trial and received the death sentence for his crimes.