In Mumia’s case, I believe his death sentence was reversed on appeal. So some of the blame falls on stupid judges.
The current governor, Corbett, just signed an execution order for Richard Baumhammers, who killed 5 people in cold blood during a shooting spree back in 2000. Wanna bet Baumhammers won't be executed?
Not quite. There was a long window of time before they found a Federal Judge willing to order his death penalty reconsidered. During that time he could, and should, have been executed. Even after the decision for reconsideration, the state could have sought the death penalty again. After consulting with Faulkner's widow, she made what she described as a heartbreaking decision to forego the death penalty. The PA Attorney General made it clear they would do whatever she wanted, but with so many witnesses now dead or unwilling to testify, getting a capital sentence was now very unlikely. Cook agreed to accept life without parole in exchange for ending all appeals.
Almost all of the blame falls on stupid judges, but Rendell had a chance to force the issue before the final appeal was made. He didn't.