I think the death penalty should be revised in all 50 States.
1. No death penalty allowed when there is only circumstantial evidence in the specific case. The burden of proof must be higher than that. Scott Peterson, in California, is an example of a recent case where there is circumstantial evidence only, yet he got a death sentence. In his case (california) everyone knows he will never be executed, but the sentence he got is still wrong. IMO anyway.
2. After someone is given a death sentence, an independent review of the entire case should be required, done within 1 year by an unbiased, all citizen board, to see if they agree with the penalty, or if they think it is inappropriate for any reason with the particular case. This board could be chosen, seated, and paid for pretty much like our jury system is used. Neither the defense or the prosecution can participate in board selection, it is done independently of the biases of either side.
3. If the board finds circumstances they don't like, they have the power to commute the sentence to life without parole. Period. End of story.
4. If they find nothing object to, that the laws have been adhered to all the way through, sentence is to be carried out within 30 days of their decision. No more 20+ years of waiting for justice.