USA plans to execute tortured detainees

If anyone had any illusions that the United States were part of civilized mankind the Bush administration took the additional step of officially seeking the death penalty for 6 Gitmo prisoners. It's not like the death penalty is anything new in the USA, nor is the USA the only country in the world which still has this uncivilized and useless practice (Japan, which otherwise appears to be generally civilized, just executed several people). No, the interesting thing here is that the Gitmo detainees are either prisoners of war, in which case they cannot be executed, or they are criminals, in which case they should not be put to trial by the USA while being detained in a location in which the USA, by its own admission, has no jurisdiction. Furthermore, since all the these prisoners were tortured (the CIA admitted waterboarding KSM and five other detainees) this begs the question of how any evidence against them was obtained. In other words, there is no possible way these men can be put to trial in any legal way, much less so sentenced to death.

All this begs the question: what exactly will these executions achieve?

Can anyone suggest an answer to this question?