DNA
The issue is perception.
You say a strand of DNA is the same, ethically, and a live human being. I say it isn't.
You say a convicted murderer is guilty. I say that legally this is true, but we are seeing, increasingly, that legally and actually are not always the same. Look at the DNA.
I also say that nobody can commute a death sentence after it's carried out. Somehow, "Oops! Sorry!" seems inadequate when faced with the execution of someone -- a live person with a face and a brain and everything -- for a crime of which he was actually innocent, guilty verdict notwithstanding.
Regards--
Mary Anne