The execution of a man later found to have been innocent should automatically generate a murder conviction for all the key players (those who could have done something) in the chain that put him to death.
So that would be the key witness at the trial, the prosecutors at that trial, the judges on the state Supreme Court, and the governor that refused to grant clemency.
The system needs to be held responsible when it knowingly makes mistakes and intentionally fails to correct those mistakes.
This saved the taxpayer a lot of money.