From what I understand of the law and the appeals process is that you can only appeal aspects of a case that fell within the original case and ruling. Recanted testimony, after the fact, as far as I can tell, will not change an appeals ruling, as long as the proper legal process, and results, came during the original trial. New evidence, especially in the case of questioned/recanted witness accounts can be tricky. They most frequently lead to a new trial. For a new trial, witness coercion would probably have to be proved in front of a judicial review.

The supreme court does not have executive powers. It hears cases and reviews ruling based on the interpretation of law and the constitution. The man had been found guilty by a jury of peers, and sentenced based on that verdict. Short of a miscarriage of law, an interpretation of the law, or clear and verified circumstances that change the verdict, the Supreme court tends to not get involved, allowing state legal and executive branches to rule in their own jurisdictions.

Personally, I don't know the circumstances of the two witnesses that have not changed their story since. Were they the two strongest witnesses? I haven't head the specific witnesses claims of coercion. But, I do know that this case and outcome is a mess. He was convicted and sentenced on the strength of 9 witnesses and no hard evidence. He was executed on that result.

It does seem odd that the load of questions and possible coercion would at least have resulted in a longer stay, or possibly having the death penalty changed to at least life in prison. Was it justice or was it a mistake? I don't think any of us will really be able to answer that definitively. And, I think that it is THAT, more than anything else, that makes people uncomfortable that he was indeed executed. People would rather be certain when it comes to ending a man's life.