Following are excerpts from the testimony of Dr. Vincent P. Guinn to the House Select Committee on Assassinations. Dr. Guinn is considered to be an expert in neutron activation analysis. I think that these excerpts should do a little to dispell the myth that neutron activation analysis (NAA), is a technique which will yield 100% certainty about the origin and composition of materials. This myth has been used by critics of the Warren Commission to impugn the validity of the lone gunmen theory. Regardless, of whether or not the WC's conclu- sions were valid, I think that, based on this testimony, those among the critics who used the results of NAA to cast doubt on this conclusion could rightly be accused of a certain level of disingenuousness. Note that all emphasis added is mine. The inclusion of ellipses indi- cates areas where I have eliminated discussion which I deemed irrelev- ant. For those who wish to read the testimony in its entirety, it is contained in the HSCA report, Vol. 1, starting on page 490. (Thanks to Tony Marsh for sending me this text.) "... Mr. Wolf: In your capacity as an expert witness did you both testify as to samples you had analyzed and performed the analysis on as well as an evaluation of analyses that other people had done? Dr. Guinn: Yes, both of them. Mr. Wolf: Approximately how many times have you testified in your cap- acity as an expert witness? Dr. Guinn: I would say approximately 50 times. Mr. Wolf: Generally, Dr. Guinn, why would one subject an evidence sample to neutron activation analysis? Dr. Guinn: It depends on the kind of evidence sample, but for many kinds the purpose is to detect various elements in the samples and compare specimens to see if they are sufficiently similar in composition that it indicates a *HIGH PROBABILITY* of common origin or, if they differ widely, a definite *PROBABILITY* of noncommon origin. Mr. Wolf: So it may be possible, by neutron activation analysis, to determine if two or more unknown evidence specimens are from the same batch or item, is that correct? Dr. Guinn: That is correct. Mr. Wolf: To use an example, if a crime had been committed and the victim hit over the head with an ax, and metal fragments were found in the skull of the victim, might you be able to analyze the metal fragments found in the skull to see if they matched the type of ax that was found in a particular person's house who is accused of the crime? Dr. Guinn: Yes; if one found the same elements at approximately the same concentrations in both, you could establish that there was a good *PROBABILITY* that it came from the same type of ax. It wouldn't ident- ify that particular ax because there might have been a hundred or so made of the same batch of metal but it would establish that particular brand and production lot perhaps. Mr. Wolf: Is it easier for you to state your conclusion that two objects are alike or is it easier to establish the conclusion that two items are not alike? Dr. Guinn: It is much easier to *EXCLUDE*; if you find two samples that differ markedly, it is easy to say *DEFINITIVELY* they did not have a common origin. If they look similar in composition, then your first statement is: "They may have a common origin", and you have to look more carefully and look at background data that you have obtained on such materials to try to even estimate a probability that they really do have a common origin. ... Mr. Wolf: How many different types of bullets have you examined by neutron activation analysis? Dr. Guinn: Approximately 165 different actual, known brands and known production lots of bullets. Mr. Wolf: Were these of different calibers as well as manufacturers? Dr. Guinn: Yes; they covered the full range of calibers as well. ... Mr. Wolf: Have you analyzed Mannlicher-Carcano bullets produced by the Western Cartridge Co. (WCC)? Dr. Guinn: Yes, I have. Mr. Wolf: When did you do these analyses? Dr. Guinn: A number of years ago. I believe I started doing the first analyses about 1973. A colleague, not at Irvine but at the University of Kansas, Dr. John Nichols, had been interested in the President Kennedy case for quite some time and he contacted me and said he had been able to acquire boxes of Mannlicher-Carcano ammunition from the four product- ion lots that had been produced by the WCC, and he was wondering if I would be interested in doing analyses on them since I had earlier anal- yzed a lot of other kinds of bullets. I said yes, and I did, and we found some *UNUSUAL* features about WCC Mannlicher-Carcano ammunition that showed it was different from most kinds of bullets. ... Mr. Wolf: Addressing your analyses, did you find WCC Mannlicher-Carcano bullets differed from most other bullets you had analyzed? Dr. Guinn: Yes; they did. Mr. Wolf: How did they differ? Dr. Guinn: Well, as of the time that I first measured them, they had a lower antimony content than I had encountered prior to that in most other bullets, because a very large percentage of bullets you do look at, commercial ones, are hardened lead, where they deliberatedly (sic) add anywhere from half a percent up to perhaps 4 or 5 percent antimony to make the lead much harder. A very large percentage of commercial bullets do have hardened lead. So we have usually found much higher antimony levels than in the WCC Mannlicher-Carcano bullets. Mr. Wolf: And Mannlicher-Carcano bullets are considered unhardened bullets. Is that correct? Dr. Guinn: "They are definitely unhardened bullets. That puts them down much lower in antimony than most bullets. Subsequently we -- in looking at a lot more brands in the interim -- did find some others that were also low, some of them lower yet in antimony, but that was one unusual feature. The other unusual feature of the WCC Mannlicher-Carcano is that there seems to be *NO UNIFORMITY* within a *PRODUCTION LOT*. That is, even when we would take a box of cartridges all from a given production lot, take 1 cartridge out and then another and then another and then another, all out of the *SAME* box -- boxes of 20, these were -- and analyze them, they all in general look *DIFFERENT* and *WIDELY* different, particularly in their antimony content. This is *NOT TRUE* of most bullet leads that we have ever looked at before, which are very uniform. In general, if you take most boxes of ammunition -- and we published on this; it is in the literature -- take a bunch of them out, you *CAN'T* tell one from the other. They all look like little carbon copies even to activation analysis, but not so with the Mannlicher-Carcano. ..." Following is the testimony of Dr. Guinn about the results of the NAA on various fragments he received from the National Archives. These frag- ments consisted of: CE399 (the "Pristine" or "Magic" bullet), CE141 (a complete, unfired bullet taken from the M-C rifle at the TSBD), CE573 (a mashed bullet still in the jacket reportedly fired at Gen. Edwin Walker), CE567 (a mashed, large bullet fragment still in its jacket reportedly recovered from the front seat of the Dallas limousine), CE843 (consisting of one larger fragment and one smaller fragment report- edly recovered from President Kennedy's brain at autopsy), CE842 (one larger fragment and two smaller ones reportedly recovered from Governor Connally's wrist during surgery), CE840 (fragments reportedly recovered from the rear floor of the Dallas limousine). "... Mr. Wolf: Was there any lead on any of the evidence samples in the Nat- ional Archives on the clothing of Governor Connally or President Kennedy that you could subject to neutron activation analysis? Dr. Guinn: Not so far as I am aware, and I did not analyze any materials from clothing at all, just these bullets or bullet fragments. ... Mr. Wolf: Dr. Guinn, I would now like to turn to some of the results of the analyses you performed for the committee and some of the conclusions you may have obtained. Turning to the items in what you characterized as group 2, first, this consisted of the alleged bullet fired at General Walker and the unfired WCC Mannlicher-Carcano cartridge. Was the unfired WCC Mannlicher-Carcano cartridge similar to the previous WCC Mannlicher-Carcano cartridges you had tested? Dr. Guinn: First of all, I am looking for the table here. Would you re- peat the question, please? Mr. Wolf: Was the unfired WCC Mannlicher-Carcano cartridge that you tested similar to the previous ones you had tested independent of the work you did for this committee? Dr. Guinn: Yes, sir; the key elements, the antimony and the silver were in the same range as the other WCC Mannlicher-Carcano samples. The anti- mony was definitely down at the lower end and the silver was up at the upper end, but it was the same general range. Mr. Wolf: And what was the composition you found in your analyses of the Walker bullet fragment? Dr. Guinn: About 17 million parts per million antimony. Each value has a little uncertainty to it, but just stating the numbers, 17 parts per million antimony, and 20.6 parts per million silver, in the Walker bull- et. Mr. Wolf: Was this similar to the composition of the unfired WCC Mannlicher-Carcano cartridge? Dr. Guinn: Yes, sir; the unfired WCC Mannlicher-Carcano cartridge which we took apart, took a little sample out of the lead; and put back to- gether again, instead of 17 parts per million antimony it was 15, in- stead of 20.6 parts per million silver, it was 22.4. These are *WELL* within the ranges of slight variation that you get from within such materials. Mr. Wolf: In your professional opinion, Dr. Guinn, is the fragment re- moved from General Walker's house a fragment from a WCC Mannlicher- Carcano bullet? Dr. Guinn: I would say that it is extremely likely that it is, because there are very few, very few other ammunitions that would be in this range. I don't know of any that are specifically this close as these numbers indicate, but somewhere near them there are a few others, but essentially this is in the range that is rather characteristic of WCC Mannlicher-Carcano bullet lead. ... (The following testimony is based on a chart entered into evidence as F-330, which shows the results based on the NAA of the evidence listed as: CE399, CE567, CE843, CE842, and CE840.) ... Mr. Wolf: Dr. Guinn, based on these results, do you have an opinion as to what type of bullets these fragments were from? Dr. Guinn: Once again, every one of these samples is in the same range, which is an unusual range, as the background WCC Mannlicher-Carcano samples that we have looked at from all four production lots. These five fall right in the midrange, in fact. They are not the highest; they are not the lowest of the antimony range, and the same is true of the silver. Mr. Wolf: Is it your opinion then that these all are fragments from WCC Mannlicher-Carcano bullets? Dr. Guinn: I think that is their most likely origin, yes. Mr. Wolf: Looking at these results, can you determine how many bullets these evidence specimens came from? Dr. Guinn: Yes, that is the really interesting part of this. I don't suppose the people in the back can see, or you up there can see, the numbers on the chart very well, but you have the report to look at. If you look at these five that are listed up here, and you first of all look at the prime or key element, which is antimony, you find of the five samples, that there are two of them that are up somewhere around 800 parts per million, and you find three others that are down just a shade over 600 parts per million. Now, after each number there is shown a plus or minus. This is only the uncertainty of that particular measurement from what we call the counting statistics. That uncertainty we can measure. Mr. Wolf: Dr. Guinn. Before we go into a more technical explanation, can you just from looking at the results, state what is the number of bullets that these evidence specimens came from? Dr. Guinn: Yes, sir, I can. Mr. Wolf: What is the number of bullets, in your opinion? Dr. Guinn: These numbers correspond to two bullets. Two of the samples have indistinguishable compositions, indicating that they came from the same bullet, and the other three particles are evidently samples from another bullet. Mr. Wolf: So it is your opinion that the evidence specimens represent only evidence of two bullets, is that correct? Dr. Guinn: Yes, sir, there is no evidence for three bullets, four bull- ets, or anything more than two, but there is clear evidence that there are two. Mr. Wolf: And which specimens that correspond, respectively, of the two bullets? Dr. Guinn: Using the CE numbers, the 399 specimen, which is the so-call- ed stretcher or pristine bullet -- it has various names -- agrees in composition both in its antimony and silver with CE-842, which are the fragments reportedly recovered from Governor Connally's wrist. Mr. Wolf: Is it your testimony that CE-399 and CE-842, the so-called pristine bullet, and the fragments removed from Governor Connally's wrist during surgery, both came from the same bullet? Dr. Guinn: Yes. One, of course, is almost a complete bullet so it means that the 842 fragments came from, in this case, the base of the bullet. Mr. Wolf: Dr. Guinn, am I correct that technically you cannot today testify to the complete validity of the so-called single bullet theory because there was no lead left in the back wound of the President or around the President's throat that would allow you to examine it and, therefore possibly determine that CE-399 passed through the President? Dr. Guinn: Yes, reportedly there were no lead fragments found in the back-to-throat wound of the President, and hence no specimens to be analyzed, so I know nothing about that particular wound. Mr. Wolf: You can, however, today state for the first time scientific- ally that CE-399 did cause the injuries to Governor Connally's wrist? Dr. Guinn: Yes sir, those two match so closely that I would say that such was the case. ... Mr. Wolf: Would you state that your conclusion is more probable than not, highly probable, or what is the degree of certainty of your con- clusion? Dr. Guinn: I would say *HIGHLY PROBABLE*, yes. I would not want to say how high, whether it was 99 percent or 90 percent or 99.9 percent. I can't make a calculation like that. Mr. Wolf: Would you state that it is highly probable that the injuries to Governor Connally's wrist came from the so-called pristine bullet? Dr. Guinn: That is correct. Mr. Wolf: Did you hear Dr. Wecht testify, in response to questions from counsel, that in his opinion it was impossible for CE-399 to have caus- ed the injury to Governor Connally's wrist, even if it hit nothing else, because CE-399 would have had to show more deformity? Dr. Guinn: Yes; I heard him make that statement. Mr. Wolf: Dr. Guinn, on the basis of your scientific analysis, do you believe Dr. Wecht to have been correct? Dr. Guinn: Well, I think that is his opinion, but like many other opin- ions and many theories, sometimes they don't agree with the facts. ... Mr. Fithian: Equally important, as your conclusions concerning Governor Connally's wrist injuries and the "pristine" bullet, is the second con- clusion you make, and that is that there is no evidence of a third, fourth, or fifth bullet represented in any of the fragments that you tested? Dr. Guinn: That is correct. Mr. Fithian: And therefore, it is highly likely -- is that the term you used to Mr. Wolf -- that all fragments tested match up with two and two bullets only? Dr. Guinn: Yes, sir. The other three samples that we have been referring to -- one being the fragments recovered from President Kennedy's brain, and then two different groups of particles found on the floor of the limousine -- those three specimens are indistinguishable from one another, but markedly different from CE-399 and 842. So there is only evidence for the presence of two different bullets. ... Mr. Fithian: Your results could be verified by others? Dr. Guinn: Yes, sir, all samples I activated and analyzed were turned right back over to the Archives, and they are right back there, and they could be reanalyzed. Mr. Fithian: Dr. Guinn, this is not meant to be an embarrassing quest- ion, but I think I must ask it. Mr. Chairman, a recent article in the New Times magazine stated that you had worked for the Warren Commission and, therefore, your conclusions for this committee would be implicitly biased. Did you even work for the Warren Commission or work for the FBI in connection with the analysis of these evidence samples? Dr. Guinn: Neither one. I think Mr. Wolf called my attention to the ex- istence of this article, which I haven't seen, and I don't know where they got their misinformation, but I never did anything for the Warren Commission, and although I know people in the FBI, I have never done any work for them. ..."