It is quite honestly a conundrum, I consider myself a civilized person and opposed the death penalty, but at the same time I am utterly convinced that there are people whose deaths would greatly benefit (or at least protect from harm) the world.
Now, I'm not saying that people should kill these individuals, but at the same time I am entirely certain that were they to die the world would be better off. Thus it becomes clear that I should appreciate their passing, but at the same time it seems clear to me that I should also appreciate anything hastening said passing which I'm not entirely comfortable with.
If someone gave me the opportunity to press a switch and see Vladimir Putin die I'm not certain whether or not I'd press it, I am, however, entirely certain that should the man pass from this earth I'd consider it greatly beneficial. That creates something of an ethical quandary, if I believe their continued existence to be harmful, am I not obligated to attempt to hasten their passing from the world? But at the same time, would I be any better if I did attempt to hasten their passing?