Chad is based on person in real life who never got punished.
The hero is angry at Chad for what he did, but decides to let it go because his obsession with revenge could poison him and because he is optimistic that Chad will suffer the consequences of his actions eventually.
Figuring that Chad will somehow weasel out of his punishment, the heroes summarily execute him.
"The universe is unfair, sometimes the guilty aren't punished, and I think this story should reflect that."
"Wow! Chad's so awesome I can't bring myself to punish him!"
Lampshaded: "You're kidding me! After all we've been through, he got away scot-free?!"
Invoked: "I'm a villain. I'm very good at escaping punishment for my actions."
Exploited: Chad murders a hero. He gets away with it. Then he robs a bank and also gets away with it. He realizes that his actions don't seem to have consequences, so he runs around doing whatever he damn well pleases.
Defied: Bob vows that Chad will not escape punishment and takes matters into his own hands to ensure this.
Discussed: "It's a cruel world; sometimes, people do get away with murder."
"You're kidding me! I read that whole thing and Chad got away with it?!"
"You know what? If you're gonna let him get away with all that shit, this world deserves to burn!"
Chad seems to be getting away with it, at least on the surface; however, deep down, he has to live with what he's done and the memories and guilt rotting away at his soul for the rest of his life. Furthermore, they have to constantly worry about justice catching up with him, meaning that he spends the rest of his life dealing with lingering paranoia. And Saint Peter isn't exactly happy with him either (The devil, however, is tickled pink to have someone to test "Murdered Ever After" on.). As a result, although he's gotten away with the crime, he's never truly happy.