The brain itself might not be a clue, but if you add to that the almost complete lack of murders and the high probability that Freud stole the ND... I'm still thinking, but I'm almost sure...
no one steals ND; a Warlock redirects a certain ND from one of the factions to someone else) ... I just want to clarify what the problem is? Isn't this the last message about Freud and dark magic? It might not be proof that Freud is a Warlock, but it could be proof that it was used on him, although for that, Freud would have had to go somewhere) However, I'm more inclined to think that Undine worked on him, who deprives abilities for two turns.