Donald B. Thomas's Dealy Plaza acoustics study, published in the British journal Science and Justice in January 2001, disputed the conclusions of the 1982 National Academy of Sciences (NAS) panel. The NAS panel used crosstalk that was simultaneously broadcast from another police radio channel to synchronize with the sound-activated dictaphone belt and concluded that the apparent "shots" were recorded one minute after the assassination had taken place.
But Thomas says the NAS panel used the wrong crosstalk to synchronize the radio channels. Furthermore, the discrepancy in time between the two channels could be explained by a "skip," which could have caused a "time warp" in the recording.
Thomas reaffirmed the conclusion of the 1978-1979 House Select Committee on Assassinations (HSCA) that a shot had come from the grassy knoll. Moreover, he took that congressional report a step further: this fourth bullet, he claimed, was the very same fatal head shot that killed the president.
The Thomas report was publicized by The Washington Post and ABC and circulated on the Internet. Some conspiracists saw it as the Rosetta Stone to unlocking the grassy knoll theory: a shot from the grassy knoll would mean Oswald did not act alone.
In the wake of the Thomas article, Norman F. Ramsey, who headed the 1982 NAS panel, brought together panel members to verify Thomas's findings. The two sides would exchange correspondence frequently. "Reading between the lines, they seemed quite peeved. … They were grasping at straws," Thomas told FRONTLINE. "But I think they are trying to get past that and get to the facts."
In an interview on Nov. 18, 2003, Ramsey told FRONTLINE that further examination of Thomas's results have vindicated his NAS panel's original argument: the fourth shot was not a gun shot at all, but an unrelated noise, perhaps static, which was recorded one minute after the assassination took place.
"We did find some errors in our original (1982) report, but our errors were small errors that did not change our conclusions," says Ramsey. "In Thomas's report we found significant errors which clearly reverse the findings of his report."