Sorry to hear about your friend PBP, but that is a real gray area that you're getting into. I don't think (or would like to think) that they don't make that mistake too often. There is an entire study that goes and researches death row inmates' innocence called the Innocence Project.
If someone was found innocent, they need to be released immediately, and restitution need to be paid. That would be a more just use of money, if it has to be spent.
However if they know guilt, no quarter should be given. In the case of Medellin, he bragged to his fellow gangbagers about it. There is no doubt he was the one. It also took long enough for him to get his day too. IIRC, he was in prison for 15 yrs before finally being executed the other day. 15 yrs of wasted taxpayers money.
I don't want this to sound like internet bravado, but this whole execution "controversy" has gotten out of hand for a long time already. If they got their facts straight, do it the most simple, efficient, cost effective way possible, and that is certainly NOT lethal injection.
Some states still have hanging and firing lines on the books, but that is meaningless because it doesn't mean they will use it anymore (that's another major problem with the system, leaving antiquated or not used laws on the books but another story).
This Pennsylvanian sends TX his best regards for having some sense.