Beg, I think my posts probably came across as though I don't care about the family's feelings because I was just writing very short posts focusing specifically on their response to his execution. So I'm sorry if I gave the wrong impression.
I do, of course, care very much that Mark MacPhail was killed and that his family will sadly be saddled with the memory and pain of his loss for the rest of their lives. A violent death of any sort is traumatic for the families and so I'm not surprised that they are still scarred by it 20 years on.
However, I do not understand their view about his execution, particularly as the evidence overwhelmingly proves that he was not the killer and that the prosecution set him up just to win the case.
Also I heard that MacPhail's actual killer is a man also on death row who confessed to someone else that he pulled the trigger. And then he conveniently failed to stand up and confess to the authorities, letting Davis die in his place. Nice one. 
I do not believe that 'anyone' should die, no matter what their involvement in a killing like this. I certainly believe that in the majority of cases, the death penalty is inappropriate. I suspect it is used in states where they imprison people for the most minor of crimes, which leads to a belief that murders need a more severe punishment to set them apart from the 'milder' crimes.
It is well documented that the USA has many innocent people on death row. Some of them are lucky enough to be released after many years of fighting, but the government does not wipe their false criminal records clean, nor pay restitution, nor enable them to resettle into normal life. So they largely end up becoming criminals, addicts or both. Their lives are ruined.
The unluckier of these innocent prisoners end up, of course, being killed for someone else's crime.
How can anyone sensible see the good in that?