I can't believe how oblivious all you guys are, you're missing out on 1 thing! I had to make an account just because it was irritating me so much!
The painting IS Rictofen!
If you hold Square (On the PS3) in front of the portraits, the character you're playing as each say something about it and on the one supposedly with the 'secret person' they say 'Oh, someones taken the picture of Rictofen out!' and if you're playing as Rictofen he says 'Errrr I can't remember this picture being taken' really quickly...
So basically everything you've said is pointless and the thread might as well be locked.