Originally posted by A P Tomlinson
View Post
Mr. EISENBERG. So the paraffin acts as a base to pick up--
Mr. CUNNINGHAM. It acts as a medium in which the foreign material is picked up from the hands.
Mr. EISENBERG. When you add the reagent, what is considered to be a positive reaction?
Mr. CUNNINGHAM. It turns a blue color.
Mr. EISENBERG. That is the cast? When you say "it," it is the cast?
Mr. CUNNINGHAM. Well, specks on the cast.
Mr. EISENBERG. Dots?
Mr. CUNNINGHAM. Yes, or an area of the cast. The theory of the test is that it is a test for gunpowder residues. Now, that is the theory, and it is fallacious, inasmuch as the reagents used in these two tests are not specific for gunpowder residues. Now, it is true that the nitrates and nitrites in gunpowder residues will react positively with diphenylamine and diphenylbenzidine, but they are not specific. They will react--these two reagents will react with most oxidizing agents.
Mr. EISENBERG. Can you give us a few examples?
Mr. CUNNINGHAM. Yes. Urine, tobacco, cosmetics, pharmaceuticals, soil, fertilizer--I have a list here of the different families or classes of compounds that will react. In addition to nitrates and nitrites, substances such as dichromates, permanganates, hypochlorites, periodates, some oxides, such as selenium dioxide and so forth. Also, ferric chloride and chromates and chlorates. The list of oxidizing agents is so large that will react--that you cannot specifically say it was a gunpowder residue.
Mr. CUNNINGHAM. Supposedly it is to determine whether or not a person has fired a weapon. In actuality, in chemistry it is a good indication that an oxidizing agent is present. The reagents have a valid use in a chemistry laboratory.
Representative BOGGS. Let me put the question this way. Given a dozen ordinary people in the ordinary walk of life, what would be the chance of a positive reaction on any one of these 12 people?
Mr. CUNNINGHAM. Excellent, sir.
Mr. EISENBERG. Has the FBI performed an experiment to determine this?
Mr. CUNNINGHAM. Yes; we have. The early sets of tests we ran with diphenylamine. And 17 men were involved in this test. Each man fired five shots from a .38 caliber revolver. Both the firing hand and the hand that was not involved in the firing were treated with paraffin casts, and then those casts treated with diphenylamine. A total of eight men showed negative or essentially negative results on both hands. A total of three men showed positive results on the idle hand, but negative on the firing hand. Two men showed positive results on their firing hand and negative results on their idle hands. And four men showed positive on both hands, after having fired only with their right hands. That was the first test we ran.
Mr. EISENBERG. A paraffin test was also run of Oswald's cheek and it produced a negative result.
Mr. CUNNINGHAM. Yes.
Mr. EISENBERG. Do your tests, or do the tests which you ran, or your experience with revolvers and rifles, cast any light on the significance of a negative result being obtained on the right cheek?
Mr. CUNNINGHAM. No, sir; 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.
Mr. CUNNINGHAM. Yes; this time we ran a control. We were interested in running a control to find out just what the possibility was of getting a positive reaction after a person has thoroughly washed their hands. Mr. Killion used green soap and washed his hands, and we ran a control, both of the right cheek and of both hands.
We got many reactions on both the right hand and the left hand, and he had not fired a gun that day.
Mr. EISENBERG. This was before firing the rifle?
Mr. CUNNINGHAM. Yes, sir. That was before firing the rifle. We got no reaction on the cheek.
Mr. EISENBERG. Also before firing the rifle?
Mr. CUNNINGHAM. Yes.
We fired the rifle. Mr. Killion fired it three times rapidly, using similar ammunition to that used in the assassination. We reran the tests both on the cheek and both hands. This time we got a negative reaction on all casts.
Mr. EISENBERG. So to recapitulate, after firing the rifle rapid-fire no residues of any nitrate were picked off Mr. Killion's cheek?
Mr. CUNNINGHAM. That is correct, and there were none on the hands. We cleaned off the rifle again with dilute HCl. I loaded it for him. He held it in one of the cleaned areas and I pushed the clip in so he would not have to get his hands near the chamber--in other words, so he wouldn't pick up residues, from it, or from the action, or from the receiver. When we ran the casts, we got no reaction on either hand or on his cheek. On the controls, when he hadn't fired a gun all day, we got numerous reactions.
Comment