Oswald in the doorway: the blog of the Oswald Innocence Campaign, by Ralph Cinque

So, who was this cop in the white shirt? He wasn't Barnett or Barnett's partner JD Smith because they were wearing dark shirts. But, look what I found:

And here's the caption that goes with this William Allen photo:
Original black and white photographic negative taken by Dallas Times Herald staff photographer William Allen. This image shows two unidentified Dallas Police officers guarding the entrance to the Texas School Book Depository on November 22, 1963 after the assassination.

Was he the cop talking to the Oswald-like figure?