I just hope Haffner will play his role very good next episode, none of the 7 have been seen alot in the show ,so even if RJ is revealed i don't think it will be something impressive, yeah we will know who RJ is but,we actually don't care about any of them because we don't know them well.
And i think its Walter Mashburn,at least i can see Lisbon's face when Patrick kill him.
