Stick with the JFK coat sleeve. Prove what we are seeing on that sleeve is the result of a 4th bullet = 2nd shooter. Then proceed to where that shot originated. Going right into an Umbrella Shooter is a "cart before the horse" situation. It would help your case if you can find visual proof placing a time stamp for the sleeve damage occurring Before the Kill Shot. On this forum, you continue to be 2nd to none when it comes to this type of JFK Assassination investigative work.
Well I haven't posted everything I've been researching. I am just reposting this since the site got hacked.
If you look at these Zapruder frames (I've tried to find the clearest frames) they, indeed, appear to show a white mark on the coat sleeve before the fatal 313 head explosion. Of course, it's not 100% this is the slashing mark on the sleeve I have noticed. This could be a coat button -- I haven't, yet, determined that.
(A) white mark on the sleeve is present before z313.
TBH, other than the clearest 253 frame, they're not really clear enough to tell what that white patch is, either button of the mark I've spotted. I haven't found decent enough frames to really tell. There are several frames that show a faint white mark.
They're in the correct area of the slashing mark on the coat sleeve, though.
And the mark wasn't there on the sleeve before the assassination. Just seconds earlier.