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

Here is another rendering of the arrow from the history-matters pdf:

And here is the comparable view from the HSCA crop of the doorway, which is considered one of the best. 

  
So, you can see that there is absolutely no mark on the forearm, and there is nothing comparable to what we see in the black space of the other either. Notice that there is darkness at the margin of the cuff of the shirt. What is that? It's probably shadow. Here is Lovelady in the shirt he was wearing, and remember that he posed in this shirt for the FBI as the shirt he wore on 11/22/63.

You see the cuff. And notice how he posed with the shirt unbuttoned. Now why would he do that? The FBI agents must have told him to do that because they were trying to duplicate the look of Doorman. What the arrow is pointing to is where someone may have pushed the shirt out to get it to spread more. A shirt doesn't necessarily sprawl open just because it's unbuttoned. Sometimes it just stays together. In this case, they knew that they needed a sprawl, and so someone may have given it a little help. And I am thinking that someone may have nudged it at that point where I drew the arrow. 

Above is a comparison of Black Hole Man and Billy Lovelady from his photo shoot with the FBI where he reportedly wore the same clothes as 11/22. Notice that the builds of the two match. The shirts match too except for the lack of stripes on Black Hole Man. I account for that by saying that they simply got rid of them, which was very easy to do. It was not the kind of shirt that you tuck in. It was squared off at the bottom with a fold, and you wore it out. I put an arrow to the bottom fold on each of them. 

That is the same guy in the same shirt, and he is Billy Lovelady. And on April 7, 1964, Billy Lovelady drew an arrow to Black Hole Man in the Altgens photo to indicate himself.