The evidence
The test that said “two bullets,” and the scientists who said it couldn’t
RECORD / AT A GLANCE
Original conclusion undercut; no new conclusion
Disputed. The two-bullet chemistry claim is now weak evidence. That removes one support for the lone-gunman case; it does not show a second gunman.
THE EVENTS / THE INVESTIGATION / THE STORY
1977
Neutron activation analysis for the House committee.
2004
The NRC finds bullet-lead comparisons cannot single out one bullet or one box.
2007
Statisticians publish new tests of the same Carcano ammunition.
2019
NIST scans CE 399 and the fragments in 3-D.
READ THE FILE
The two-bullet finding.
Are Carcano bullets as distinctive as assumed?
Open an article for its evidence, labeled AI assessment and numbered sources. Read the complete static edition ↗
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The lead chemistry behind that claim has been undermined; it no longer proves two bullets.
Who says it: Vincent Guinn, the House committee.
OPEN THE RECORD
Numbered citations in each article identify the relevant sources. These records have different purposes and evidentiary weight.
The committee’s review of the rifle, the wounds and Oswald.
Why compositional bullet-lead matches cannot single out one bullet.
Statistical challenge to the bullet-lead evidence that the fragments came from only two bullets.
3D scans of CE 399 and the fragments for researchers.
The examiner’s description of the scanning project.
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The two-bullet finding.
Neutron activation measures trace elements in bullet lead. Testing for the House committee, Guinn compared CE 399 with the fragments. The committee concluded it was “highly likely” the wrist fragments came from CE 399 and found evidence of only two bullets. [1]
In 2004 the National Research Council reviewed the FBI’s bullet-lead method in criminal cases and found such compositional matches cannot reliably tie a fragment to a particular bullet or box. [2]
What we can’t tell you. The NRC review addressed FBI casework, not Guinn’s JFK tests directly.
The committee’s review of the rifle, the wounds and Oswald.
Why compositional bullet-lead matches cannot single out one bullet.
Are Carcano bullets as distinctive as assumed?
In 2007 Cliff Spiegelman and colleagues tested bullets reportedly from the same batch as those used in the assassination and found matches within a box much more likely than the House testimony said. One of their ten test bullets matched one or more assassination fragments. That, they wrote, means the matching fragments “could have come from three or more separate bullets.” They called for re-testing. [1]
The fragments were scanned in 3-D by the National Institute of Standards and Technology in 2019 so they could be studied without handling. [2]
What we can’t tell you. Re-testing the original fragments has not been done.
Statistical challenge to the bullet-lead evidence that the fragments came from only two bullets.
3D scans of CE 399 and the fragments for researchers.
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