Oswald murdered Kennedy.
Why was the patsy murdered?
Not too mention that the family of that Secret Service agent sued Donahue for libel and won...
It accounts for the ballistic and wound evidence, and doesn't require outlandish conspiracies under every bush.
And accidents happen, especially when weapons are involved.
I point out again, this is Real Life™ we are talking about here; not cinema, which is usually mistaken for it by image-besotted children of modern times.
I do wish that agent had managed to remove a couple of LHO's front teeth with the thing. It would have made for a different world, imho.