Once again, my argument is NOT about the "fuk stik", it is not about how heinous the crime was. It is about the society, and the individuals in that society whose job it is to kill the criminal. And about the lessons taught to the kids and random passer-bys who bear witness to the execution on the street or on TV. It is about the wife of the prison guard whose turn it was to kill an inmate that day. All would be scarred by these various implementations of the death penalty.
From the fundamentalist's point of view, the soldier lying dead on the ground fifty feet away was, while on deployment, busy killing his fundamentalist brethren. To him, the soldier just got what he had coming. From that perspective, the only difference between the action of this blood-soaked killer and the policeman who shoots him and watches him bleed out is the decreased time between the action and the revenge killing.
You may want to toss aside morals in this case. You may want to skip boring & expensive legal proceedings and simply chop his head off. But an educated and moral society does not support those actions. Those are the actions of societies we disdain. Our country should not torture. We should teach that killing is wrong.
This is not a good time for grey zones, "These people can be killed in the following ways..." or "We can torture if...." That just opens the door to allow rationalization and speeches of justification by folks we don't like killing and torturing people we do like, and then pointing to our example as a blueprint.
Otherwise we should go ahead and make the death penalty more efficient, even if it means we kill an innocent person every now and then. But if we do, we should realize that we are no different from our enemies save for our incomes, quality of internet access and dialect.