The Wizard sent me a NBC video, a retrospective about their coverage of the assassination. In it, you see Ruby being led down the hall on the 3rd floor, and led into the Homicide bureau to get to Fritz' office. But then, it's followed immediately with the same thing in which he's coming from the opposite direction.
So, that's Ruby, and he's about to turn to his left/our right to get through the door, and you can see the direction he came from.
Below he does the same thing but approaching from the opposite direction.
Obviously, it had to be spliced because he couldn't go through the door and then be in the hall approaching the door. They did these things, and they didn't expect anyone to think about it, and I'm sure most people don't.
Then, it goes immediately to the image of Bookhout by the elevator with the three detectives.
What I notice is that on this one, they really blackened his eyes. Bookhout looks like a freakin' raccoon.
And that is ridiculous. Why would his eyes be so blackened while Boyd's were not?
They did that because that is James Bookhout on the right, and if his eyes were showing, there would have been no chance of passing him off as Jack Ruby.
Here is a frame from it that the Wizard added some illumination to:
Look how ridiculous his eyes look, especially his right eye on our left. It's obviously blackened. They got out the black paint.