There were NO eyewitnesses of Jack Ruby at the scene- except for lying cops. And there is no doubt that they lied. Leavelle described actions that he took which clearly did not happen- according to the films. Graves said that Oswald was handcuffed to himself- which he clearly was not. Combest said that Oswald communicated with him in the jail office by shaking his head- while everyone else denied any consciousness, awareness, responsiveness, or movement by Oswald.
And, thanks to Amy Joyce, we know now that when Jack Ruby was first told that he shot Oswald, his first words were, "My God, My God," not "I hope the son of a bitch dies; I did you all a favor" as the lying cops maintained.
Melvin Belli, had he opened his eyes and mind, could have made mincemeat of those lying cops on the witness stand.
"Officer Leavelle, you claim to have seen and recognized Jack Ruby in advance, but the films clearly show that you didn't even look in his direction, and you had no reaction to him at all until after the shot was fired. Your Honor, I request permission to show the jury a film, and it would be to rebut Officer Leavelle's testimony."