Board Thread:General Discussion/@comment-1904000-20130613053934/@comment-4913740-20130621080216

Crony wrote: It has been stated earlier actually http://metalgear.wikia.com/wiki/Thread:32622#16 At this point really there is no doubt left that this character is Miller. It's just can't be anyone else. I know it's been stated already, that's why I put the picture up; so that it could actually be seen.

And yeah, at this point it seems like it must be Miller.