Assuming that what WSJ reported is indeed true, that it is widely accepted hypotheses within intelligence community (Reuters could not verify they).
What and how intelligence community would know that? By the fact that someone was talking about exchange? And this preclude Putin from ordering execution before elections how? I actually do not believe that this “intelligence community” is that stupid to hold it as “wildly held belief”. That’s bad WSJ reporting.
What else do we know? That Russian officials deny that? The same officials that denied presence of Russian military when they captured Crimea? If anything, them denying from the first day shows opposite situation. Normally, one would investigate it, but it is as if they knew the answer from day 1.