The problem is human life is worth far less than any of us want to believe people put $$ on it all the time, its sad but it is reality.
If you kill anther then you should forfeit your own life simple as that.
So because some people hire hit men and whatnot, that makes human life valueless? Or of minimal value? No. Human life is all important. It's the most important thing any of us have. I'd gladly give up all I have to guarantee myself longer life. I think anybody would, assuming they are of sound mind. Killing another isn't enough to be yourself killed. An eye for an eye sends the world blind. Senseless killing is terrible, but doing unto others what they have done to you isn't always a great way to live.