The Ethics of the Execution Participation:Why a Physician and Why Not the Jury?

I heard on the news that it would be a physician who is to determine if Stanley Williams is dead after given the IV chemicals. If the news report is correct, this represents the unethical use of a physician. Think.. what happens if the physician finds that Williams is not dead? Then the physician's evaluation is going to be used as the basis to administer more poison to insure death. Thus the physician is not simply confirming death but participating in the completion of the death sentence. It's plain wrong! If the death sentence is a morally correct act then why is it that at virtually every step in the final minutes of the process including the pressing of the three buttons to administer each chemical, a different person is to carry out each step so that no single person can assume responsibility for the end result. If the act was morally virtuous, certainly only one person would be necessary to claim the virtuousness. My other question involves those who are participating beyond the physician. Why is it that the very persons who have legally established that Williams should die, such as the judge, members of the jury and the Governor amongst others shouldn't be the ones to actually perform the execution? Is it really another way to avoid "dirtying" their hands from consequence of their decisions? You can see which way I stand on the whole ethics of this business. ..Maurice.