If killing the innocent is considered a wrong deed, then killing the guilty must be a righteous act.
That argument, while logical from a certain standpoint, completely falls apart in the context of modern society.
Only those with proper authority can pass judgment on others. If anyone could do so freely, it would lead to countless disastrous situations.
Take a simple example: A person sees a thief attempting to steal something and immediately rushes over to punch the thief in the face. Unfortunately, the blow lands on a fatal spot, and the thief drops dead on the spot.
Another person witnesses this scene and assumes that the one who struck the thief is a murderer who acted with malicious intent.
