'I rape you, you kill me, welcome to humanity'. Round and round and round we go, when it stops, well, probably not until the apocalypse. The problem with this kind of logic is it's a slippery slope, especially if you're the one in power, it's far easier to just get rid of something than it is to deal with it, and the very easily becomes cyclical, ie: He killed someone's brother, because he raped someone's sister who stabbed someone's uncle who was probably trying to molest her anyway. Killing people is a short term solution, though it is very convenient, Stalin was a great fan of it: 'Death is the greatest solution, no man, no problem'. The logic of vengeance and retribution solves nothing, other than achieving a temporary self-righteous sense of satisfaction for the wronged party, it neither solves or deters the behavior, and simply engenders a kill or be killed mentality.
I'll leave you with this. You want to be really brave? Then try to understand why people kill, rape and torture each other, and then try to prevent it through altering the environments that create such people. But of course that's way to hard for most people, and of course, it also requires we look at the 'darkness' in our own souls, and that scares the shit out of a lot of people.
Killing solves nothing. Go in peace, my fellow human being.