I saw Mortal Error too.....it was based on the book with the same name. His theory went that the entrance wound in JFK's skull from the third shot (which he claimed) was only 6mm wide. The ammo Oswald was shooting was 6.5mm ammo. So he said it had to be made by a smaller round. Thats when he focused in on that one secret service agent with the AR15 which shoots 5.56mm ammo. He said when the agent fell backwards the gun accidently fired a round and that was the third shot that klled JFK.

The agent sued but it was thrown out of court because he waited too long to file the lawsuit but when it was republished as a paperback he sued again and the publisher made him an out of court settlement i believe it was.