When I wrote my comments, I had only skimmed through parts of the book: "Russo attempts to explain the violent backward motion of Kennedy's head and upper body with the jet-effect theory (p. 298). This theory says the right-frontal explosion that we see in the Zapruder film pushed Kennedy violently backward and to the left. This is most unlikely. Dr. Larry Sturdivan, a wound ballistics expert, testified to the HSCA that this right-frontal explosion would have produced little motion, and that what small amount of movement it might have generated would have pushed Kennedy straight to the left, not backward and to the left. Several other scholars have rejected the jet-effect theory, including two physicists. Proponents of the single-shooter scenario have long had trouble explaining why Kennedy's upper body moves violently backward if he was supposedly shot only from behind. Another theory offered to explain this apparent contradiction is that Kennedy's backward motion resulted from a neuromuscular reaction. This was the theory that Dr. Sturdivan offered to the HSCA as his explanation for Kennedy's rapid backward movement. But this theory is just as problematic and implausible as the jet-effect theory. I asked Dr. Robert Zacharko, a Canadian professor of neuroscience, about the neuromuscular-reaction theory. He said it was absurd and that those who advance it don't understand neuromuscular reactions or how the brain works. I've seen war films and execution films that show men being shot in the head. In those films (at least in all the ones I've seen) the victims always go limp immediately, and their heads move in the same direction as the bullet. The most logical explanation for Kennedy's fierce backward movement, assuming the existing Zapruder film is pristine, is that it was caused by a shot from the front. Dr. Michael Kurtz:"