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

The man by the elevator with the policemen at 6:20 in The Killing of Lee Harvey Oswald is NOT Jack Ruby. His features differ from Jack Ruby, markedly.

Ruby had a pyramidal nose, which translates to a triangular shape in the two-dimensional photo: Bookhout had a narrow nose. Ruby had a long forehead; Bookhout's was short. And, Ruby's whole face was longer while Bookhout's was rounder. They are definitely different men; strikingly different. It is not hard to tell them apart. 

And the man on the right is James Bookhout, which you can see here, even though both images were altered. 

That is the same guy, and I doubt that most people look that much the same after 26 years. It is over; the jig is up. FBI Agent James Bookhout was the Garage Shooter of Lee Harvey Oswald.