....
However, I will say again that I think there is very strong evidence that he was aware of the murder before the body was found, and that he participated in a coverup of the murder.
I don't the evidence even supports that conclusion. However, those would be much smaller crimes (probably obstruction of justice). If he actually participated in a coverup after the fact, it's much more likely that he would have admitted it, made a deal and testified against the actual murderer rather than claim complete innocence and be sentenced to death. That's just not how people behave in the real world.