The big problem with the death 'penalty' is prisons are BIG BUSINESS. Run by corporations with lobbyists. We can't be killing lots of people who could be rotting in a cell earning the major shareholders a new yacht.
It's far more humane to put people down than keep them in a box until they die. We don't have the humanity to do what we'd do for a dog that bit the postman once too often. Would you lock the dog in a cage just big enough for the dog to lie down in for the rest of its natural life, or would you have it put down?
We could pick up the pace a bit by SWIFTLY executing the condemned. Say 30 days after the gavel strikes, you either die or join the regular prison population for life?
People who rape or kill in prison need to just be put down, too. No waiting, just move straight to the head of the line!
Three strikes law? Why not simply snuff 'em instead of dumping them in a prison 'forever'?
Illegal aliens who commit infamous crimes need to die. Period. Doesn't matter where you came from, if you commit murder, rape, kidnapping, arson, build a bomb, etc. you get a fair trial, and if you lose, then we kill you. You didn't bother to fill out the right form and wait in line before you came, we won't bother with any 'appeals'. Straight to the lethal injection table with you.
While we're at it, every single prison cell should come equipped with a functional noose securely attached to the ceiling. Some problems can take care of themselves.
As far as 'innocent' people, we all die someday. Even if exonerated, your life is basically done after you've been in prison. Want a job? Fill out this application! Once the prospective employer sees 'prison' on the form, you're out. Doesn't matter if you got a full pardon from the governor and Oprah gave you a big hug.