There is the bald man with the shredded dress pants and shirt (in many photos running from one of the bomb scenes). But (to my recollection) he has no beard.
Was he in a crowd shot? There are sites that had 1,000s of photos up (reddit, 4chan) maybe worth going back and looking some more.
Had to be on here only place I read, but have went to several links from here, and will be checking those, thanks, maybe be nothing but never know