that "saw only good in his captors until the last second of his life". read that back to yourself a few times - could it also not read "he was one of them, and at the last moment they double crossed him".
I hate to speculate about stuff like this, given that he died in this way and this all may be just coincidence and conjecture, but something is so strange here.
Having no more evidence at this point, I'd say this is the most likely and most obvious hypothesis that should be pursued in search of the truth. Way too many "coincidences." [Things are seldom more complex than what they appear after scratching the first layer below the surface] Deals w the devil never play out.