Even if he were a prisoner, I must say, he must have been a kind hearted one.

Assume this event occurred in the past and that it is unreal (as I am not sure whether the person who helped me was actually a prisoner). Shouldn't it come under 3rd conditional (past unreal condition). If so, shouldn't the sentence be

Even if he had been a prisoner, I must say, he must have been a kind hearted one.

To my ears, the first sentence sounds better. Please comment.