For the nerves, I'd guess. I have no issue with his execution, but it's got to be scary as hell to walk into a room where you're going to be killed.
Anybody seen any good source material on his 'redeemed' behavior in prison? I have heard stories which suggest that he terrorized his fellow inmates and that the staff was relieved to be rid of him.
He was put in isolation for a while after he threw cleaning chemicals in a guard's face.