Well, considering what we know at the end of the game, it seems pretty clear that he did it himself. Think about how he tidily he was arranged -- arms and legs in front, a single piece of tape over his mouth -- and how bizarre his story is -- two men ran in, tied him up, and left without doing anything else? Yeah, right. My guess is that he was trying to give himself an alibi so Nancy wouldn't suspect him of ransacking her room. Pretty lame, spy guy.