The good news about the neutron-activation analyses of bullets and fragments from the JFK assassination

Kenneth A. Rahn, Sr.
Center for Atmospheric Chemistry Studies
Graduate School of Oceanography
University of Rhode Island
Narragansett, RI 02882-1197
26 August 1996

Prepared for submission to COPA’s Third Annual National Conference
18–20 October 1996, Washington, D.C.

    Considering how hard researchers are struggling to better understand the JFK assassination, any piece of good news comes as a welcome surprise. After spending much of the last two years studying the two sets of neutron-activation analyses (NAA) of bullets and fragments from the assassination (done by the FBI in 1964 and the HSCA in 1977), I can now report that a piece of good news is indeed emerging—the fragments appear genuine, both analyses are of high quality and agree closely with each other, and together they provide a simple, straightforward picture in which two Mannlicher-Carcano bullets from one rifle account for every fragment retrieved and analyzed. The joint results also provide strong evidence for two groups of fragments, with members of each group being indistinguishable from each other but the groups being clearly distinguishable. The first group contains the Parkland bullet (CE 399) and Connally’s wrist fragments; the second group, the fragments from JFK’s brain, the front seat of the limousine, and the rear carpet of the limousine. In the past, the difficult statistical aspects of these data coupled with the variable composition of MC bullet lead have prevented researchers from calculating the all-important probability that the two groups are chemically different. I have found a way to overcome these difficulties and can show that this probability is greater than it might appear at first glance: at least 90% and quite possibly greater than 95%.
Because these analyses have received such bad press for many years (claims of switched fragments, misinterpreted data, etc.), I have paid special attention to these criticisms. I can report that they all seem unfounded, having sprung from incomplete understanding of how NAA actually works. Several of these misunderstandings have been needlessly perpetuated for many years by researchers’ citing other researchers rather than persons familiar with NAA.
What do these results mean? In contrast to claims made over the years by various WC supporters, the existence of the first group neither proves the single-bullet theory nor provides strong direct evidence for it. By showing that the fragments from Connally’s wrist are indistinguishable from the Parkland bullet, this first group provides strong evidence consistent with the SBT but equally consistent with an independent hit to Connally. The second group of fragments effectively ties the head shot and all fragments found in the limousine to the Mannlicher-Carcano. The real importance of the NAA data, however, is the "baseline" picture of the assassination they provide—two bullets, one rifle—that logically must be taken as the operative explanation until stronger evidence is provided for a more complex view.

AV: Only overhead transparencies

    Kenneth A. Rahn has a B.S. in chemistry from MIT (1962) and a Ph.D. in meteorology from the University of Michigan (1971). For the last 25 years he has worked as an atmospheric chemist both in the U.S. and Europe. During that time his principal analytical tool has been neutron-activation analysis. He has been at the University of Rhode Island since 1973, and is now a tenured full professor at its Center for Atmospheric Chemistry Studies, which he cofounded in 1980. He has been interested in the JFK assassination, particularly its scientific aspects, since 1992.