Everyone answer this question?

when is it morally acceptable to kill I'll give you an example if charles manson got released from prison on a technicality and he was gonna kill more people so lets say that you kill him by cutting off his limbs and letting him bleed to death then you put the body in like a public place and you didn't kill any innocent people but you broke a cops nose and arm while escaping into the sewers now keep in mind by doing this you saved dozens of lives