I've always thought we could farm out our death row inmates to a Bolivian or Thai or Nigerian prison, say at $30,000 per annum, and keep them alive on the chance that the eye witness will have a change of heart. It's a plus for the Bolivians, it's no fun for the prisoner, and it is reversible in case some mouth breathing DA committed a pooch screw 'cause he/she wanted to be governor.
It might actually be a deterrent if some gang banger from Chicago thinks he could spend life in some Thai lockup, a long way from his homies.