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

 Now we can see the mechanics of it in this Secret Service reenactment. So, if Oswald had used that door, the way the man did, the door would still have been open as he passed through the room. In the second picture, we're seeing him but mainly through the open door. And the door wasn't open when Baker saw Oswald. By the time the door closes completely, the man is gone. So, since Baker saw Oswald through that pane of glass when the door was closed, it means that Oswald didn't use that door. He used the door on the office side.