 Critic Mark Vogler wrote that The Killing Joke provided the Joker "with a sympathetic back story as it presented some of the villain's most vile offenses." Moore's rendition of the Joker's origin employs elements of the 1951 story "The Man Behind the Red Hood" (Detective Comics # 168), which established the concept of the Joker originally having been a thief known only as the Red Hood. The tragic and human elements of the character's story, coupled with his barbaric crimes as the Joker, portray the character as more of a three-dimensional human being. During an interview with Salon, Moore explained that Joker's psychotic nature could have been caused by a "bad decision" in his life.
