One of the most crucial aspects of the death penalty is that it is reserved for people that physically kill other human beings. The mere fact that the laws of a US state even allowed the possibility of a death sentence for someone that did not personally kill someone else is a serious problem. That's before even considering the possibility that he may have been wrongly convicted.

Personally, I don't understand why we have the death penalty in the US. First, the possibility of a wrongful conviction is real. Second, we have prisons that are brutal and allow very few escapes, making life in prison a far worse punishment than the death penalty. Remember that the death penalty for a prisoner these days consists of falling asleep and not waking up. There simply are no valid reasons to impose the death penalty in a country like the US.