Did the Paraffin Test Show Oswald Had Not Fired a Rifle?

During his questioning Lee Harvey Oswald was administered a paraffin test by W. E. Barnes of the Dallas Police Department. In this test warm paraffin, which is applied to the skin to open up its pores, collects contaminants. If the suspect had fired a gun, one potential contaminant would be the nitrates from gun powder residue. Once the paraffin hardens, either diphenylamine or diphenylbenzidine is introduced to the paraffin cast, which will turn it blue in the presence of nitrates. Thus, the presence of blue dots on the paraffin casts is evidence that the suspect had fired a gun.

A paraffin test was applied to Oswald's hands and right cheek; his hands reacted positively, whereas his cheek did not. Since shooting a rifle should have exposed his right cheek to gunpowder, the negative reaction is often cited as evidence that he did not fire a rifle. One such example of a writer citing this test as proof Oswald did not shoot a rifle is Oglesby, from The JFK Assassination: The Facts and the Theories, p. 283:

Nitrate tests performed on Oswald when he was arrested supported his claim that he had not fired a rifle in the previous 24 hours.
Mark Lane makes a similar assertion in Rush to Judgment, p. 149:
A positive response on both hands and a negative response on the face is consistent with innocence. It is also consistent with Oswald's claim that he had not fired a rifle on November 22.
And that treasure trove of conspiracy lore, Jim Marrs' Crossfire, makes a similar claim:
Another important piece of evidence involved a paraffin test made on Oswald the day of the assassination. The results of this test presented evidence that Oswald may not have fired a rifle that day, yet these results were downplayed and even suppressed by the federal authorities.

. . .

Oswald's hands both reacted positively to the paraffin test, indicating the presence of nitrates. But a cast of his right cheek showed no reaction. Any competent defense attorney would have pointed to this test as evidence that his client had not fired a rifle. (pp. 442-443)

The ballistic matches of bullet fragments and CE399 to C2766 showed that they all came from Oswald's rifle but say nothing about whether he actually shot it. And the paraffin test seemingly absolved him of that, right?

Wrong, as it turns out. Before the assassination, the FBI had conducted experiments showing the unreliability of paraffin tests. FBI expert Cortlandt Cunningham testified to this in front of the Warren Commission (3H487):

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.
It is evident that false positives and false negatives occur with the revolvers. After the assassination the Warren Commission directed the FBI to run the same experiment using the C2766 rifle and ammunition which was identical to what was found in the Texas School Book Depository. Cunningham related the results of that experiment (3H494):

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.

EISENBERG: So to recapitulate, after firing the rifle rapid-fire no residues of any nitrate were picked off Mr. Killion's cheek? 
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. 
Cunningham had explained earlier why a false negative could arise with the rifle (3H492):
EISENBERG:  A paraffin test was also run of Oswald's cheek and it produced a negative result.
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?
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. 
To summarize, both false positives, from nitrates present in ordinary substances other than gunpowder, and false negatives, due to the sealed-chamber design of the C2766, arose in paraffin tests.

On page 151 of Rush to Judgment, Mark Lane writes that "Confronted with but one legitimate interpretation—that the paraffin test results were consistent with innocence—the Commission concluded that the test . . . was 'completely unreliable.'" The real reason that the Commission discounted paraffin tests is obvious: they were of no value in determining whether a suspect had fired a weapon.

To his credit, in a footnote on page 151, Lane did mention the negative result on the cheek of FBI agent Killion in the FBI tests. Unfortunately, he proceeds to dismiss this fact by stating that "For the test to have been valid, it would have been necessary for the rifle to be in contact with the agent's cheek when fired. The Commission does not even suggest that the rifle was fired in that fashion." His citation for this statement is the Warren Commission Report (WCR), pp. 561 to 562. On those Warren Commission Report pages only one statement pertaining to the firing of the rifle is found:

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.
Sure, the Report does not mention whether the rifle contacted Killion's cheek during the test. But how else is a rifle held in the act of shooting? Is Lane suggesting that Killion shot the rifle while holding it at arms length?

Now, if you're a conspiracist, any test done by the FBI, especially those done for the Warren Commission, lacks credibility. But a quick check of standard forensics texts yields a similar conclusion. For example, Vincent J. M. Di Maio, in Gunshot Wounds: Practical Aspects of Firearms, Ballistics, and Forensic Techniques (New York: Elsevier, 1999) writes on p. 327 about the paraffin test's unreliability:

The ability to determine whether an individual has fired a firearm is of great significance in the investigation of both homicides and suicides. Thus, over the years a number of tests have been developed in an attempt to fill this need. The first such test was the "paraffin test" also known as the "Dermal Nitrate" or "diphenylamine test."1 It was introduced in the United States in 1933 by Teodoro Gonzalez of the Criminal Identification laboratory, Mexico City police headquarters. In this test, the hands were coated with a layer of paraffin. After cooling, the casts were removed and treated with an acid solution of diphenylamine, a reagent used to detect nitrates and nitrites that originate from gunpowder and may be deposited on the skin after firing a weapon. A positive test was indicated by the presence of blue flecks in the paraffin. Although this test may give positive results on the hands of individuals who fired weapons, it also gives positive results on the hands of individuals who had not fired weapons because of the widespread distribution of nitrates and nitrites in our environment. The paraffin test is in fact nonspecific and is of no use scientifically.
Conspiracy theorists often claim that the paraffin test produces "false positives" (a positive test when the person hasn't in fact fired a weapon), but no "false negatives." This conveniently allows them to dismiss that Oswald tested positive on his hand (which might indicate that Oswald shot Tippit with a revolver), while claiming that the negative result on Oswald's cheek proves he didn't shoot Kennedy with the Mannlicher-Carcano rifle.

Unfortunately, the FBI tests (above) — as well as Di Maio's observation that the test "often but not invariably" gives positive results with people who have fired a gun — disprove the conspiracy theorist's claim. Both "false positives" and "false negatives" are possible, and indeed very common.

For example, Charles O'Hara and Gregory L. O'Hara, in Fundamentals of Criminal Investigation (5th Edition), p. 771, explain and note some problems with the paraffin test:

The dermal nitrate test (paraffin gauntlet test) is a procedure designed to determine whether a suspect has recently discharged a firearm. Melted paraffin is brushed over the "shooting" hand of a suspect until a thin coat is obtained. The glove can be built up in layers by using thin sheets of fabric until it is about 1/8 inch thick. The diphenylamine reagent is prepared by adding 10 cubic centimeters of concentrated sulfuric acid to 2 milliliters of distilled water. To this is added 0.05 grams of diphenylamine. The reagent is dropped on the paraffin mold with a pipette. Dark blue specks appearing on the inner surface of the cast indicate a positive reaction. . . . Theoretically, the diphenylamine reagent is used to test for the presence of nitrates, which are contained in the residue of gunpowder blown back on the hand in discharging the firearm. . . .

Objections: There are several scientific objections to the test as described above in its simplest form. The role of the nitrate on the hand is that of an oxidizing agent. Other strong oxidizing agents can produce the same effect. Hence, launderers, chemists, pharmacists, and other persons handling bleaches or other oxidizing compounds may have materials on their hands which would yield a positive reaction. Thus the test does not necessarily indicate the presence of nitrates, but establishes merely that an oxidizing substance is present on the hand. In brief, the test is non-specific. Another objection is concerned with the fact that there are many non-incriminating sources of nitrates such as fertilizers, explosives, tobacco, urine, and cosmetics. Certain foods also contain nitrates. Finally, some experimenters have found that it is possible to obtain a negative reaction from the hand of a person who has recently fired many rounds of ammunition. . .

Thus, there is plenty of evidence that the paraffin test gives false negatives.

In one of the wacky episodes that often mark Internet discussion of the assassination, a pro-conspiracy poster named Lisa Pease dismissed the material quoted above. She claimed that of course forensics texts would say that, since they were written after the assassination, and would not be willing to admit that Oswald was innocent. Apparently, she believed that evil minions of the conspiracy had succeeded in subverting the writers of forensics texts.

In fact, the paraffin test was widely dismissed as ineffective long before the assassination. For example, we find the following passages in Firearms Investigation, Identification, and Evidence by Hatcher, Jury, and Weller (The Stackpole Co., Harrisburg, Pennsylvania: 1957). The authors discuss the paraffin test on pages 435 through 438, including FBI and other controlled tests of the method:

They have found the most alarming inconsistencies. For instance, a woman who could not remember ever having had a firearm in her hand in her life gave positive tests for both hands. Further, men who fired guns all day were sometimes able to remove most of the evidence of this firing by an ordinary washing of their hands with the usual soap provided in wash rooms. (435)
The authors then reprinted an article from the FBI Law Enforcement Bulletin for October, 1935 (Note the date) with the comment that the article is "still completely authoritative on this subject." (435) In the article they discuss false positive results, and then note: "On the other hand, it is well to know the limitations of the diphenylamine test which are due to the fact that in a great many instances one may fire a revolver or pistol without leaving any trace of gunpowder on the hand which may be detected by this test." (pp. 436-437)

A follow-up article in the FBI Law Enforcement Bulletin from 1940 reaches the same conclusion.

But, if the paraffin test was so useless, why did the Dallas Police bother to administer it? The Warren Commission asked FBI expert Cunningham about this (3H494):

FORD:  Based on your testimony this morning, and what you have told us in the last few minutes, why are paraffin tests conducted and how extensively are they? 
CUNNINGHAM:  Many local law-enforcement agencies do conduct these tests, and at their request the FBI will process them. They take the cast and we will process them. 

However, in reporting, we give them qualified results, since we frequently will get some reaction. Numerous reactions or a few reactions will be found on the casts. However, in no way does this indicate that a person has recently fired a weapon. Then we list a few of the oxidizing agents, the common ones, such as in urine and tobacco and cosmetics and a few other things that one may come in contact with. Even Clorox would give you a positive reaction.

FORD: Is this a test that has been conducted by law-enforcement agencies for some time. Is it a new test?
CUNNINGHAM: No, sir; the first test that I reported on here were conducted in 1935. 

There may be some law-enforcement agencies which use the test for psychological reasons.

DULLES: Explain that.
CUNNINGHAM: Yes, sir; what they do is they ask, say, "We are going to run a paraffin test on you, you might as well confess now," and they will — it is —
Mr. DULLES: I get your point.
The Commission also pressed the Dallas Police to explain why they had administered the test. When J. C. Day, the Department's forensics expert, was asked "Had you ever done a paraffin test on a face before?", Day responded "No; actually—had it not been for the particular type of case and this particular situation here—we would not have at this time. It was just something that was done to actually keep from someone saying later on, 'Why didn't you do it?'" (4H276).

The Dallas police had done paraffin tests on hands before, because positive results on hands were fairly frequent. The Warren Commission record doesn't show whether the Dallas police ever got convictions based on "evidence" from this test.

Some authors, in the wake of the assassination, portrayed the Dallas police to be a bunch of incompetent hicks. While unfair in most cases, with Oswald the Dallas police administered a test that had no scientific basis and was useless as evidence.

If the Dallas cops look bad on the issue of the paraffin test, what are we to say of conspiracy authors, who could learn the uselessness of the test by a casual inspection of any standard forensics text, but who nevertheless claim it shows Oswald's innocence?

More Modern Versions of the Test

While the traditional paraffin test (as used on Oswald in 1963) was largely useless, more modern versions of the test are quite useful, and improvements in the chemistry of the test have largely eliminated false positives.

But what about false negatives? An authoritative text cautions that:

. . . a negative test for GSR [gunshot residue] is meaningless, as (a.) tests are only positive in about half of the cases when an individual is known to have fired a gun, (b.) tests are usually negative in relationship to rifles and shotguns.2
Thus, the Warren Commission was correct in dismissing the paraffin tests performed on Oswald's hands and cheek. Conspiracy authors, in saying that the tests proved Oswald innocent of firing the rifle, are claiming something flatly at odds with standard forensics texts — texts that guide good law enforcement practice.

This, on the part of conspiracy authors, is known as "buff forensics:" inventing forensics principles for the purpose of getting Lee Harvey Oswald off the hook.

1 Cowan, M. E., Purdon, P. L. A study of the "paraffin test." J. Forensic Sci. 12(1): 19-35, 1967.

2Vincent J. M. Di Maio and Suzanna E. Dana, Handbook of Forensic Pathology, 2nd ed. (Boca Raton, FL.: CRC Press, 2007), 151.

Newsgroup posts of Felix Chen, Tony Simon, and John L. Hartman were used on this page. 

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