There is still the head going back during the fatal shot - despite any explanations as to why this might have happened, when in most cases the impact from the front would have caused this. Although there have been suggestions of missing frames from the video.
Or ...
But the modeling study (and underlying dynamics and conservation laws) presented in this paper, in corroboration of the autopsy findings [25], do imply that President Kennedy was not hit by a hypothesized gunshot from the front. The conclusion is an important one given that the hypothesized existence of a shooter in front of the limousine (viz., on the Grassy Knoll) has been the primary physical foundation for virtually all conspiracy conjectures to date on the topic.13 As a parting note, while the simple one-dimensional physical models presented in this paper were derived for application to a special case study (viz., the Kennedy Assassination), the underlying physical principles provide an approximate quantitative description of the interaction between a high-speed projectile (slowed by an intervening atmosphere) and a heterogenous body comprised of bone and visco-elastic tissue (viz., the human head), and may also form a basic conceptual basis for understanding the wounding mechanisms involved in such interactions. [source]