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

You realize that they were really worried that Oswald's hand-clasping in the doorway was going to give it away that it was him. So, they came up with the idea that Oswald's arm coming down was really the black guy's arm going up hailing a tamale vendor. That scratching of a hand that you see on the right is not real, and it is laughable. For one, the hand is rotated the wrong way; the thumb is on the wrong side. For two, the elevation of the arm is too steep, too close to vertical. For three, the rolled-up sleeve of his shirt is the exact same greyscale as his naked skin. The Idiot Sprague actually bought that shit, and other idiots followed, but fortunately, not too many. 

But, it goes to show you how concerned they were that Oswald's habit of clasping his hands in front was going to unravel the whole wicked scheme. Force of habit is a powerful thing.