publication of its report revealed that the FBI had arranged for bullet CE 399 and the various fragments found in the car and in Governor Connally's wounds to be examined using neutron activation analysis (NAA). NAA is a precise, non-destructive method of determining the relative concentrations of trace elements in a sample of matter. The data from the tests performed for the FBI were inconclusive as to the origins of the fragments. In 1978 the HSCA asked physicist Vincent P. Guinn to review the NAA data and conduct new tests. Guinn did so and presented his results and analysis to the Committee. Guinn stated that initially he agreed with the earlier conclusion. However, after examining the old and new NAA data further, he concluded that all the fragments probably came from two bullets, one of which was the whole bullet, CE 399. Guinn compared antimony concentrations of Exhibits CE 840, 843 and 567 with that of Exhibits CE 399 and 842 and concluded that the data supported the single-bullet theory in that all the bullet lead in the car and wounds originated from no more than two bullets. Conclusions about the single-bullet theory from the NAA analysis Whether the NAA data can be used to actually exclude the possibility that there were fragments from more than two bullets in the wounds and the car has been the subject of controversy. Ken Rahn of the University of Rhode Island, a chemist and meteorologist who has a long-standing interest in the Kennedy Assassination, maintains that the NAA data excludes a "three bullet hit" and proves the SBT actually occurred. His analysis was published in 2004 co-authored with Larry Sturdivan, a Warren Commission and HSCA ballistics expert. Rahn/Sturdivan say that the possibility that the wrist fragment CE 842 (with an antimony concentration of 797 ± 7 ppm) did not come from the base of the whole bullet CE 399 (the sample from which had an antimony concentration of 833 ± 9 ppm) is so statistically improbable as to be excluded as a reasonable possibility. However, in an article published in July 2006 in the Journal of Forensic Sciences by Erik Randich and Patrick M Grant, the authors took a much different view of the NAA data and the metallurgical profile of the Mannlicher–Carcano ammunition. The authors found errors in the analysis by Guinn: Thus, elevated concentrations of antimony and copper at crystallographic grain