Every human action has some consequence.
When an action is in error, we fallible creatures try, or at least know we should try, to correct it - to right the wrong. A few actions, though, fall into that dark pit of irreversibility. Snuffing out the life of another human being is one of those. Whether done in hot anger or in cold reason, once done, it is final. . We know that the state cannot at the present time be certain.