Four bullets were recovered from the body of Officer Tippit.[A10-71] In Nicol’s opinion one of the four bullets could be positively identified with test bullets fired from V510210 revolver, and the other three could have been fired from that revolver.[A10-72] In Cunningham’s opinion all four bullets could have been fired from the V510210 revolver, but none could be positively identified to the revolver[A10-73]—that is, in his opinion the bullets bore the revolver’s rifling characteristics, but no conclusion could be drawn on the basis of microscopic characteristics.[A10-74] Cunningham did not conclude that the bullets had not been fired from the revolver, since he found that consecutive bullets fired in the revolver by the FBI could not even be identified with each other under the microscope.[A10-75] The apparent reasons for this was that while the revolver had been rechambered for a .38 Special cartridge, it had not been rebarreled for a .38 Special bullet. The barrel was therefore slightly oversized for a .38 Special bullet, which has a smaller diameter than a .38 S. & W. bullet. This would cause the passage of a .38 Special bullet through the barrel to be erratic, resulting in inconsistent microscopic markings.[A10-76]
Based on the number of grooves, groove widths, groove spacing, and knurling on the four recovered bullets, three were copper-coated lead bullets of Western-Winchester manufacture (Western and Winchester are divisions of the same company), and the fourth was a lead bullet of Remington-Peters manufacture.[A10-77] This contrasts with the four recovered cartridge cases, which consisted of two Remington-Peters and two Westerns. There are several possible explanations for this variance: (1) the killer fired five cartridges, three of which were Western-Winchester and two of which were Remington-Peters; one Remington-Peters bullet missed Tippit; and a Western-Winchester cartridge case and the Remington-Peters bullet that missed were simply not found. (2) The killer fired only four cartridges, three of which were Western-Winchester and one of which was Remington-Peters; prior to the shooting the killer had an expended Remington-Peters cartridge case in his revolver, which was ejected with the three Western-Winchester and one Remington-Peters cases; and one of the Western-Winchester cases was not found. (3) The killer was using hand-loaded ammunition, that is, ammunition which is made with used cartridge cases to save money; thus he might have loaded one make of bullet into another make of cartridge case.[A10-78] This third possibility is extremely unlikely, because when a cartridge is fired the cartridge case expands, and before it can be reused it must be resized. There was, however, no evidence that any of the four recovered cartridge cases had been resized.[A10-79]
The Struggle for the Revolver
Officer McDonald of the Dallas police, who arrested Oswald, stated that he had struggled with Oswald for possession of the revolver and that in the course of the struggle, “I heard the snap of the hammer, and the pistol crossed my left cheek * * * the primer of one round was dented on misfire at the time of the struggle. * * *”[A10-80] However, none of the cartridges found in the revolver bore the impression of the revolver’s firing pin.[A10-81] In addition, the revolver is so constructed that the firing pin cannot strike a cartridge unless the hammer (which bears the firing pin) has first been drawn all the way back by a complete trigger pull.[A10-82] Had the hammer gone all the way back and then hit the cartridge, it is unlikely that the cartridge would have misfired.[A10-83] It would be possible for a person to interject his finger between the hammer and the cartridge, but the spring driving the hammer is a very strong one and the impact of the firing pin into a finger would be clearly felt.[A10-84] However, the cylinder and the trigger are interconnected and the trigger cannot be fully pulled back if the cylinder is grasped.[A10-85] Therefore, if Oswald had pulled on the trigger while McDonald was firmly grasping the cylinder, the revolver would not have fired, and if the gun was grabbed away at the same time the trigger would have snapped back with an audible sound.[A10-86]
The Paraffin Test
During the course of the interrogation of Lee Harvey Oswald following the assassination a paraffin test was performed by the Dallas police on both of his hands and his right cheek. The paraffin cast of Oswald’s hands reacted positively to the test. The cast of the right cheek showed no reaction.[A10-87]
To perform the paraffin test, layers of warm liquid paraffin, interleaved with layers of gauze for reinforcement, are brushed or poured on the suspect’s skin. The warm sticky paraffin opens the skin’s pores and picks up any dirt and foreign material present at the surface. When the paraffin cools and hardens it forms a cast, which is taken off and processed with diphenylamine or diphenylbenzidine, chemicals which turn blue in the presence of nitrates. Since gunpowder residues contain nitrates, the theory behind the test is that if a cast reacts positively, i.e., if blue dots appear, it provides evidence that the suspect recently fired a weapon.[A10-88] In fact, however, the test is completely unreliable in determining either whether a person has recently fired a weapon or whether he has not.[A10-89] On the one hand, diphenylamine and diphenylbenzidine will react positively not only with nitrates from gunpowder residues, but nitrates from other sources and most oxidizing agents, including dichromates, permanganates, hypochlorates, periodates, and some oxides. Thus, contact with tobacco, Clorox, urine, cosmetics, kitchen matches, pharmaceuticals, fertilizers, or soils, among other things, may result in a positive reaction to the paraffin test. Also, the mere handling of a weapon may leave nitrates on the skin.[A10-90] A positive reaction is, therefore, valueless in determining whether a suspect has recently fired a weapon. Conversely, a person who has recently fired a weapon may not show a positive reaction to the paraffin test, particularly if the weapon was a rifle. A revolver is so constructed that there is a space between the cylinder, which bears the chambers, and the barrel. When a revolver is fired, nitrate-bearing gases escape through this space and may leave residues on the hand.[A10-91] In a rifle, however, there is no gap between the chamber and the barrel, and one would therefore not expect nitrates to be deposited upon a person’s hands or cheeks as a result of his firing a rifle. As Cunningham testified:
Mr. Cunningham. * * * I personally wouldn’t expect to find any residues on a person’s right cheek after firing a rifle due to the fact that by the very principles and the manufacture and the action, the cartridge itself is sealed into the chamber by the bolt being closed behind it, and upon firing the case, the cartridge case expands into the chamber filling it up and sealing it off from the gases, so none will come back in your face, and so by its very nature, I would not expect to find residue on the right cheek of a shooter.[A10-92]
The unreliability of the paraffin test has been demonstrated by experiments run by the FBI. In one experiment, conducted prior to the assassination, paraffin tests were performed on 17 men who had just fired 5 shots with a .38-caliber revolver. Eight men tested negative in both hands, three men tested positive on the idle hand and negative on the firing hand, two men tested positive on the firing hand and negative on the idle hand, and four men tested positive on both their firing and idle hands.[A10-93] In a second experiment, paraffin tests were performed on 29 persons, 9 of whom had just fired a revolver or an automatic, and 20 of whom had not fired a weapon. All 29 persons tested positive on either or both hands.[A10-94] In a third experiment, performed after the assassination, an agent of the FBI, using the C2766 rifle, fired three rounds of Western 6.5-millimeter Mannlicher-Carcano ammunition in rapid succession. A paraffin test was then performed on both of his hands and his right cheek. Both of his hands and his cheek tested negative.[A10-95]
The paraffin casts of Oswald’s hands and right cheek were also examined by neutron-activation analyses at the Oak Ridge National Laboratory. Barium and antimony were found to be present on both surfaces of all the casts and also in residues from the rifle cartridge cases and the revolver cartridge cases.[A10-96] Since barium and antimony were present in both the rifle and the revolver cartridge cases, their presence on the casts were not evidence that Oswald had fired the rifle. Moreover, the presence on the inside surface of the cheek cast of a lesser amount of barium, and only a slightly greater amount of antimony, than was found on the outside surface of the cast rendered it impossible to attach significance to the presence of these elements on the inside surface. Since the outside surface had not been in contact with Oswald’s cheek, the barium and antimony found there had come from a source other than Oswald. Furthermore, while there was more barium and antimony present on the casts than would normally be found on the hands of a person who had not fired a weapon or handled a fired weapon, it is also true that barium and antimony may be present in many common items; for example, barium may be present in grease, ceramics, glass, paint, printing ink, paper, rubber, plastics, leather, cloth, pyrotechnics, oilcloth and linoleum, storage batteries, matches and cosmetics; antimony is present in matches, type metal, lead alloys, paints and lacquers, pigments for oil and water colors, flameproof textiles, storage batteries, pyrotechnics, rubber, pharmaceutical preparations and calico; and both barium and antimony are present in printed paper and cloth, paint, storage batteries, rubber, matches, pyrotechnics, and possibly other items. However, the barium and antimony present in these items are usually not present in a form which would lead to their adhering to the skin of a person who had handled such items.[A10-97]