The five basic bullets and fragments from the JFK assassination have been analyzed for their elemental composition three times, all with the goal of being able to associate the little fragments with the big ones and thereby determine how many bullets hit Kennedy and Connally. They were first analyzed by the FBI the night of the assassination, by optical emission spectroscopy, a relatively coarse and insensitive technique by today’s standards. The results were semiquantitative at best, and are useless. That, however, did not stop critic George Michael Evica, then of the University of Hartford, from misinterpreting them and rendering useless the major part of his 1980 book that depended on them. They were next analyzed by the FBI again in May 1964, this time using the new technique of nondestructive neutron activation analysis (NAA). Their results were much better than often portrayed. They did, however, contain a serious systematic error that prevented the FBI, in this their first venture into NAA, from recognizing it. Because they were not sure of their results, Director J. Edgar Hoover decided to keep secret the fact of the analysis and its results. The fragments were third analyzed by Vincent P. Guinn, of UC Irvine, for the HSCA in September 1977. His results confirmed those of the FBI, but were not as extensive because of compromises in his analytical scheme. The two sets of NAA results show that the five fragments fall into two tight groups that are meaningful physically—one corresponds to fragments from the body shot (the SBT), the other to fragments from the head shot. There is no direct evidence for more than two bullets. Together with the ballistic markings on one large fragments from each of the groups, they offer an extremely high probability that all the fragments came from Lee Harvey Oswald’s Mannlicher-Carcano rifle to the exclusion of all other rifles. When combined with the proper physical interpretation of the President’s double movement after the head shot, NAA offers a potent, simple picture of two bullets from the rear, from the same rifle, against which no credible evidence has emerged. The onus then falls on critics to offer some reason why this scenario should not be accepted, which they have not been able to do for nearly forty years. A few years ago, however, one serious challenge was raised by Wallace Milam, to the effect that antimony, Guinn’s major tracer element in the WCC/MC bullets, was sufficiently heterogeneous in quarters of test bullets to invalidate the two-group interpretation by smearing the groups into one another. This criticism has been taken up by many critics who are interested in the subject, and is attractive enough on its face to convince them that the NAA data mean nothing. This school has failed to take proper account of the implications of the tight groupings, however, which are too narrow to have arisen by chance. It is as if the two heterogeneous bullets produced fragments that were homogeneous. A very simple mechanism, which is also physically meaningful, is to imagine the lead core of a jacketed bullet breaking at only one or two places, and the fragments all being shorn from the highly irregular surfaces of the break. This mechanism would produce homogenous fragments because they all came from very near each other. Given the greater complexity of all competing scenarios, the strong working hypothesis has to be exactly that: the men were hit by only two bullets, both from Oswald’s rifle, one that passed through both bodies (the SBT) and one (and only one) that hit JFK in the head, from the rear.
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