I can prove that this image is bogus. You know that the cop is grabbing Oswald around his arm. The cop's arm is in the space between Oswald's arm and his torso. That's how you grab someone around the arm. So, we know where Oswald's arm is, and where his forearm is.
Where else could that cop be grabbing Oswald except around his arm? And why is Oswald's arm bent like that? Is it because his hands were handcuffed behind his back? But, wait! I don't know that his hands were EVER cuffed behind his back. But, when they are, it doesn't look like that. It looks like this:
The arms remain mostly straight with just a slight bend. You don't see the elbow bent at 90 degrees.
Now, if that's not Oswald's arm as I have it labelled, what is it, and where the hell is his arm? Important: his hands were NEVER cuffed the way they appear to be in that picture. Important.