THE MAN WHO DIDN’T TALK

And other tales from the new Kennedy assassination files

So who's right? If you don't care to choose your science on the basis of whether it confirms your pre-existing views on Kennedy's murder, you have to consider the two slightly different arguments going on here.

To oversimplify slightly, Garwin and co. focus on the timing of the supposed shots observed on Dictabelt #10, while Thomas focuses on the nature of the sound impulses found on the recording. On these issues, the dueling scientists reach different conclusions that are logical -- and open to legitimate question.

In my subjective view, Garwin and co. have posed a big problem for Thomas but not so big as to exclude a gun shot from the grassy knoll beyond the limits of plausible conjecture.

After all, we already have the photographic evidence from the Zapruder film showing Kennedy hit by a bullet that snapped his head backwards and drove him sideways into the arms of his wife. To say that a bullet fired from the knoll would have pushed Kennedy backward is well within the limits of plausible conjecture, regardless of what you think about the acoustic evidence. If FBI agents Sibert and O'Neill saw a more massive head wound than what's shown in the autopsy photographs, that too might be more evidence of a shot from the front.

"Hold Everything Secure"

"Don has got to confront a basic problem," says Michael O'Dell, one of the leading experts on the JFK acoustics evidence. "How can a 'shot' be fired from the grassy knoll at the same moment that police are responding to the call 'hold everything secure'? It can't."

O'Dell is an unobtrusively brilliant man who lives with his wife in Fresno, California. By day, he runs the technology department of an insurance company. O'Dell is not one of those people drawn to the assassination by interest in the Kennedys or true crime stories or political conspiracies or the Mafia or anything like that -- and that is a great strength of his work. He does not embody the paranoid style in American politics. He embodies the empirical style sorely lacking in most JFK coverage. His methods are detached, analytical, polite and methodical. His e-mail exchanges with Thomas are civil.

He plays the tape of the shots on his desktop computer. You cannot actually hear the shots amidst the drone of engines and snippets of conversation between various Dallas cops. The screen displays the wave forms of the shots that killed Kennedy. Or not. The scratchy sound of the tape, the spiky green lines, made me think of how narrowly scientific methods captured the reality of a president blasted in the head by a bullet and dying in his wife's arms.

---

---

O'Dell focuses on the phenomenon known as "cross talk." First, he explains how the Dallas Police Department (DPD) communications system worked. The DPD operated two radio channels. Channel I was for normal police radio traffic and Channel II was assigned for the use of the presidential motorcade. Each channel was recorded by a different device in the DPD radio room. Channel I was recorded on a Dictabelt and Channel II on a Gray Audograph machine. Both machines worked by engraving a track into a plastic medium. The Dictabelt used a rotating cylinder and the Audograph used a flat disk, similar to a phonograph record. The sounds on the two channels are not synchronized because Channel I was recorded constantly while Channel II was voice-activated.

"Crosstalk occurred when sounds from one channel were picked up by a microphone tuned to the other channel," he explained.

An accident of history created the whole controversy. A DPD motorcyclist somewhere in Dallas "had a defective microphone button that caused it to continuously transmit over a five-minute period during which the assassination took place." This accidental transmission began at 12:28 that day, about two minutes before the assassination.

"If this motorcycle had been part of the motorcade," as one dispatcher thought, "it might" -- emphasize might -- "have picked up sounds of the gunshots" and transmitted them to headquarters where they would have been recorded on Channel I. "If true, those sounds could be used to determine how many shots were fired, their timing, and using echo location methods, where the shots came from."