You know this case better than I. However, ...
your claim that he continued to plan/execute murders after the exchange is, to the best of my knowledge, an unproven claim. So, he was, in fact, executed without due process. For, he was clearly not executed for the crimes of which he was convicted.
Mind, this isn't my fight, just pointing this out.
bcnu,
Mikem
The soul and substance of what customarily ranks as patriotism is moral cowardice and always has been...We have thrown away the most valuable asset we had-- the individual's right to oppose both flag and country when he (just he, by himself) believed them to be in the wrong. We have thrown it away; and with it all that was really respectable about that grotesque and laughable word, Patriotism.
- Mark Twain, "Monarchical and Republican Patriotism"