It just occurred to me that maybe, instead of this being a Ruby impostor who was actually there, maybe it's just a photographic impostor in which they plastered another man's face over Ruby's.
I can only speculate as to why they would do that. We certainly get the impression that Oswald's shooter had a roundish head.
It looks like a ball, doesn't it? But, Ruby's face and head were not as round and ball-like as the shooter's. Ruby's face was longer.
So, maybe in this shot below, Ruby's face looked particularly out of sync with the shooter's. Maybe they plastered another face over it.
It was a still shot. It's like they were all posing for the camera. And that's weird in itself. Who does that with a murderer? And what if Ruby broke out into a smile? They couldn't have that.
But, for whatever reason, if the image was unsuitable in its natural state, why didn't they just destroy it?
Who the pluck knows? We're dealing here with very arrogant people who thought that they could get away with anything.
But, whether it was a real impostor (a funny juxtaposition of words, I admit) or just a photographic impostor, it's just as incriminating. Either way, it means that Jack Ruby was not the shooter of Lee Harvey Oswald.