Catholics are supposed to be Pro-Life.
Killing convicted inmates ends their life in death, therefore violating God's Mercy. But allowing brutal rapists and murders, terrorists, and anarchists, to manipulate the system, and live with three hot's and a cot, on the taxpayer dime, while putting Correctional Officers and employees, not to mention other inmates, at great risk is a travesty of Justice, God's Justice.
So what is a Catholic to do?
Obviously, we are supposed to listen to the teaching of the Church--Apostolic Authority given by Christ. But in our 'cafeteria' American society this is both a challenge and an affront to the sensibility of the Catholic/Christian infected with postmodern secular progressivism.
Furthermore, it is hard to pin down the direction of the Church's teaching concerning capital punishment. For the Church has always reinforced the Pauline interpretation of Scripture which interprets the state's right (as God's agent of justice) to punish heinous crime. Yet, recently, Church documents (particularly, from St. John Paul II) have emphasized the opportunity to decrease the incidences of capital punishment because of improvements in the capacities of correctional facilities to house and retain the worst criminals.
Therefore, unless the Church makes an ex-Cathedra statement on capital punishment, the Catholic is to understand that certain crimes, and the criminals who commit them, are above the pale of strict Justice and necessitate the termination of the killers life, for public, and prison, safety, since recent history has proven that there are some people hell-bent on destroying our American way of life. Yet, on the other hand, with the American Justice system bearing warts of incompetence, and prejudice, all others beside the most heinous of criminals (i.e., the criminal with one incident of murder) should be the recipient of strict Justice (life in prison without parole), and strict Mercy in the sparing of His Life.
I know this will not please the idealistic liberal in search of tender mercy for convicted murderers. I also realize that this will not please the hard right winger seeking societal vengeance. Also, this will open Catholics to an attack from anti-Catholic bigots who say we are two faced as Pro-Lifers, but truth is sometimes a paradox.
Just consider that we were saved by the worst crime perpetrated in history.