Oswald was on the first fllor when the shots were fired according to photos and testomony. The rifle was taken into the room where his body was kept, corrupting the evidence.
No witneses placed Oswald on the first floor. If you think otherwise please name them. As for the photo, the person claimed to be Oswald was correctly identified as someone else, Billy Lovelady.
http://mcadams.posc.mu.edu/oswald_doorway.htm