The scientific single-bullet theory

10 August 2001

      One of the frustrations of the JFK assassination is that it has not been possible to test the single-bullet theory (SBT) scientifically. To be sure, the second half of the proposed trajectory, the track through Governor Connally’s back and right arm into his left thigh, can be tested by comparing the neutron-activation analysis (NAA) data from the fragments in his wrist with the composition of the end of CE 399. The match of antimony in these two samples, to the exclusion of all the other fragments tested, can be combined with the ballistic match between CE 399 and Oswald’s rifle to create a three point trajectory—the bullet started on the sixth floor of the depository, passed through Mr. Connally’s torso and arm, and ended up in his thigh. This part of the trajectory can now be accepted as fact.
That’s the easy part. The problem has traditionally been the first part of the trajectory, through the president’s back/neck and out his throat. Since no fragments of lead were left there, presumably because the bullet was not tumbling enough to distort it and squeeze lead out the base and allow tiny fragments to be shorn off, this part of the track could not be tested by NAA. Instead, weaker arguments of consistency with the idea had to be advanced, such as general alignment of the men and the nonpristine nature of Connally’s first wounds. Perhaps the strongest argument used the downward track through Kennedy’s neck to assert that the bullet then had to enter Connally or damage the car, and since it didn’t damage the car it entered Connally’s back. This approach depended on the downward trajectory created by the bullet’s entering above the shoulder blade. If, however, the bullet entered some inches lower, as claimed for example by those who reason from the holes in the coat and shirt without accounting for bunching, the trajectory could be upward relative to the car, and the bullet might fly out without hitting Connally or the car.
But there is a simple way to show that the track through Kennedy’s back/neck must be downward. One need only grant that that the bullet entered from the rear, and it is done. The key is that any shooting location to the rear of the car that is above street level produces a downward trajectory relative to the car and its three-degree downward inclination. A shooter could not have fired from the street anywhere near the corner of Elm and Houston because of the crowds and the other cars in the motorcade. Any elevation at or above the second floor in the buildings near there produces a downward trajectory and restores the original line of reasoning that the bullet must have hit Connally or the interior of the car, and since it didn’t damage the car it entered Connally. In simplest terms, NAA and the geometry of Dealey Plaza establish the SBT scientifically.
One obvious rejoinder to the above is that the bullet could have been deflected upward as it fragmented the tip of one of the lower vertebrae of JFK’s neck. But this damage was far too slight to have deflected the bullet significantly, and it was not even clear that the bullet actually struck the bone. The damage has been described as a grazing or brush-by fracture.
The immediate import of this result is obvious—the SBT is now scientific fact. A broader message is that it was made possible by our new understanding of the NAA. The broadest message is perhaps that the web of physical evidence for the simple one-shooter, two-hit scenario continues to tighten while the lack of hard evidence for anything else remains deafening by its silence. It appears only a matter of time before all the critical physical evidence will be shown to speak in unison for the simple, obvious nature of this crime. One guy on his lunch break, three shots, two hits, done.
I repeat, however, what I tell my JFK class many times each semester—show me hard evidence of conspiracy and I'm first in line to embrace it. But it hasn't appeared in 37 years, and every year of absence lessens the probability that anything is out there to be found.

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