It's interesting to note that the increased "popularity" of the death penalty among US residents seems to coincide with the increase in media coverage. As people read and see accounts of particularly brutal crimes, they become more accepting of harsher punishment.
I suppose the question goes back to the core purpose of our justice system. If it is punishment, then capital punishment makes sense.
If it's revenge, it also makes sense.If someone I love were brutally murdered, I would want the person responsible dead. Heck, I want "revenge" if I see someone else's child murdered,never mind my own!
If it's a deterrent, I'm not so sure it's effective, except for that particular individual. Certainly, he or she will never kill again! However, other continue to kill without much thought about the consequences.
If it's rehabilitation, the death penalty doesn't make sense; it assumes that rehabilitation is impossible. If rehabilitation is possible, the question becomes, rehabilitated to what? If someone has been a "criminal" since childhood, that's not likely to change. Therefore, he/she will be right where he/she was before prison...a predator, if you will.
Granted, some people might be executed unfairly. A small percentage might even be "innocent." I'm always reminded of the Bob Marley line, "I shot the sheriff, but I did not kill the deputy!" Basically, he is lamenting the fact that he's being punished for the killing of the deputy.
And yes, I have also been in Sunday School discussions, etc about the murder vs kill translation. It's obvious that capital punishment was common throughout the bible, with God's "permission."
The question then becomes, do we risk taking an innocent life to protect society as a whole? That is a question that every society has and will continue to wrestle with forever. The pendulum will continue to swing back and forth, depending upon the actions of it's members.
We give immunizations to our children, with the full knowledge that some will be injured or killed, but do it for the greater good of all. Should we feel guilty about doing the same thing to protect the morally healthy from the criminal predators?