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Clearing up the difference between Paraffin tests and NAA

Oswald was given Paraffin tests on both hands and on the right cheek.

This test has often been labelled as having no value because it produces what is inaccurately labelled "false positives".

This is nonsense.  The test is very accurate at detecting nitrates.  If someone is given this test and it comes back positive, it is 100% proof that the person has come into contact with nitrates.

Nitrates are found in a number of things; only one being gunpowder residue.  This test cannot determine the exact source of the nitrates.

Neutron Activation Analysis differs in that it tests for substances commonly found in gunshot residue - or in other words, the total emissions, not just from the gunpowder. This includes tiny particulates of metals such antimony and barium.

And therein lies the confusion.

  • Paraffin tests - nitrates only
  • NAA - antimony, barium, lead vapor from primer, fouling and projectiles

So when Dallas police and FBI experts testified that you are highly unlikely to find gunpowder residue on the cheek of someone who had fired a rifle, this is not at all at odds with the paraffin casts later being tested using NAA and finding antimony and barium on the cheek cast. Same goes with the NAA tests done on test firers.  The gunpowder simply cannot escape the chamber, but other substances are still emitted from the weapon and can land on the cheek.

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So what does this mean in terms of the Oswald case?

  1. That Oswald's hands or casts had come into contact with nitrates from an unknown source (paraffin test)
  2. That Oswald's right cheek or cast had come into contact with substances found in gunshot residue (the later NAA tests)

Can we determine the source of the nitrates on the hand casts? Yes.

Oswald's palm prints were taken just prior to the paraffin being applied to hands and cheek. An inkless pad was used for the palm prints.  Such pads use colorless nitrate solutions.  This was all done outside of lab setting (specifically inside Fritz's office) where it was not possible to wash hands between the two procedures. This doesn't mean that some nitrates did not come from sources other than just the ink pad, but the deliberateness of these two procedures together tends to suggest the police had doubts or actually knew that no nitrates would be found unless they made certain of it.

The NAA tests showing gunshot on test firers is immaterial since the paraffin test on Oswald could only only test for gunpowder reside

The NAA tests on Oswald's cheek cast showing typical particles found in gunshot residue was invalidated due to these particulates being found on both sides of the cast suggesting contamination from unknown sources.

Conclusions

A positive paraffin test on the hands only shows the possibility of Oswald having fired a hand gun. However, as shown, we know the true source of the nitrates was the inkless print pad.

The purposefulness of doing both tests one straight after the other, indicates the police were making sure that the hands would be positive.

The NAA tests on test firers is a red herring as it is attempting to compare apples (NAA tests) with oranges (paraffin tests).

The NAA tests on the cheek cast would be useless to any prosecution case because of the contamination.

The Paraffin test is a VALID test, but only if your intention is to indicate the possibility of someone having fired a weapon.

Generally, a test on hands showing a lack of nitrates would be very good evidence of innocence. It would constitute proof if carried out quickly enough.

In the specific case of Oswald, the manner in which the test was carried out is evidence of a frame.

 

Attached is part of a conversation from another forum showing the type of confusion I am talking about.

One person quotes testimony from FBI expert Eisenberg correctly states that nitrates won;t escape the chamber of a rifle and therefore, doing a paraffin test on the cheek (as was done with Oswald) was useless.

Some responded that this was not true because 7 out of 7 volunteer shooters of a Carcano had extensive gunpowder residue on their cheeks, thus proving that rifle leaked.

The problem is that the test used here was NAA - not a paraffin tests. Therefore what was tested for was not gunpowder residue (nitrates), it was gunshot residue -- which includes material from the primer, fouling and projectile.

Paraffin tests are not the same as NAA and gunshot residue and gunpowder residue are not interchangeable terms.

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