Dear John Blake:
Read your question. Enclosed with this short letter is my answer.
Of course, the reason is even more simple: One is guilty. One is innocent. I’ll leave it to the inferentially challenged to decipher which is which.
And let it be known that this writer takes no pleasure in the death of anyone for any reason. However laws are written to emphasize the behaviors that society deems acceptable and punishment is to deter people from following the dictates of a sin-stricken heart, a temporary yet necessary tool since the gentle whisper of the human conscience is too weak for some.