Death is just an easy way out for some prisoners. Let them rot in jail. Give them the worst of conditions for the rest of their lives ( though it doesn't always happen now does it?)
Plus I feel sorry for those people who really were innocent, they paid the ultimate price, while the real murderer got away. At least if the wrongly accused is still alive, then during some course of the jail term, some evidence proving him innocent can get him out. You can bring back a dead innocent person.