Thanks John for the solid photographic evidence.
Hi Steve yeah, when you have the original negative it's all over red rover!
There's telltale signs of grain differentiation when any two images are combined, the first problem is at this microscopic granular level you can't just cut out Oswald's head and stick it on someone else because unless Oswald's face/chin/whatever was taken at the exact same distance then the grain size that makes up the photos will be different and without the the same angle of sun on the Oswald face composite, then we have another problem.
Also at this microscopic level you can see the bleeding between edges which with traditional cut and pasting would require a fair amount of post processing which would further degrade the film grain and make it nothing like similar original film stock.
It's undeniable, it's Oswald and he's holding the weapon that murdered the President.
JohnM