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Washington Post | | Read the study

Study backs theory of grassy knoll,
  New research puts chance of second JFK gunman at 96%

President John Kennedy smiles at crowds lining his motorcade in
Dallas on Nov. 22, 1963. Minutes later, the president was assassinated as
his car passed through Dealey Plaza.
By George Lardner Jr.
March 26

"The House Assassinations Committee may have been right after
all: There was a shot from the grassy knoll. Either way, that,s "beyond a reasonable doubt., "
House Assassinations Committee        

THAT WAS THE KEY finding of the congressional investigation that concluded
22 years ago that President John F. Kennedy,s murder in Dallas in 1963 was
"probably ... the result of a conspiracy. A shot from the grassy knoll
meant that two gunmen must have fired at the president within a
split-second sequence. Lee Harvey Oswald, accused of firing three shots at
Kennedy from a perch at the Texas School Book Depository, could not have
been in two places at once.

       A special panel of the National Academy of Sciences subsequently
disputed the evidence of a fourth shot, contained on a police dictabelt of
the sounds in Dealey Plaza that day. The panel insisted it was simply
random noise, perhaps static, recorded about a minute after the shooting
while Kennedy,s motorcade was en route to Parkland Hospital.

       A new, peer-reviewed article in Science and Justice, a quarterly
publication of Britain,s Forensic Science Society, says the NAS panel,s
study was seriously flawed. It says the panel failed to take into account
the words of a Dallas patrolman that show the gunshot-like noises occurred
"at the exact instant that John F. Kennedy was assassinated.

       In fact, the author of the article, D.B. Thomas, a government
scientist and JFK assassination researcher, said it was more than 96
percent certain that there was a shot from the grassy knoll to the right
of the president,s limousine, in addition to the three shots from a book
depository window above and behind the president,s limousine.


       G. Robert Blakey, former chief counsel to the House Assassinations
Committee, said the NAS panel,s study always bothered him because it
dismissed all four putative shots as random noise even though the three
soundbursts from the book depository matched up precisely with film of the
assassination and other evidence such as the echo patterns in Dealey Plaza
and the speed of Kennedy,s motorcade.

"This is an honest, careful scientific examination of everything we did,
with all the appropriate statistical checks, Blakey said of Thomas,s work.

       "It shows that we made mistakes, too, but minor mistakes. The main
thing is when push comes to shove, he increased the degree of confidence
that the shot from the grassy knoll was real, not static. We thought there
was a 95 percent chance it was a shot. He puts it at 96.3 percent. Either
way, that,s beyond a reasonable doubt.,

       The sounds of assassination were recorded at Dallas police
headquarters when a motorcycle patrolman inadvertently left his microphone
switch in the "on position, deluging his transmitting channel with what
seemed to be motorcycle noise. Using sophisticated techniques, a team of
scientists enlisted by the House committee filtered out the noise and came
up with "audible events within a 10-second time frame that it believed
might be gunfire.

       The Warren Commission had concluded in 1964 that only three shots,
all from behind, all from Oswald,s rifle, were fired in Dealey Plaza as
the motorcade passed through. But the House experts, after extensive
tests, found 10 echo patterns that matched sounds emanating from the
grassy knoll, traveling carefully measured distances to nearby buildings
and then bouncing off them to hit the open motorcycle transmitter.

       They also placed the unknown gunman behind a picket fence at the
top of the grassy knoll, in front of and to the right of the presidential
limousine. The House committee concluded that this shot missed, and that
Kennedy was killed by a final bullet from Oswald,s rifle. Thomas, by
contrast, believes it was the shot from the knoll, seven-tenths of a
second earlier, that killed the president.



       The NAS panel, assigned to conduct further studies after the
committee closed down, said in 1982 that the noises on the tape previously
identified as gunshots "were recorded about one minute after the president
was shot.

       The NAS experts, headed by physicist Norman F. Ramsey of Harvard,
reached that conclusion after studying the sounds on the two radio
channels Dallas police were using that day. Routine transmissions were
made on Channel One and recorded on a dictabelt at police headquarters. An
auxiliary frequency, Channel Two, was dedicated to the president,s
motorcade and used primarily by Dallas Police Chief Jesse Curry; its
transmissions were recorded on a separate Gray Audograph disc machine.

       The shooting took place within an 18-second interval that began
with Curry in the lead car announcing on Channel Two that the motorcade
was approaching a triple underpass and ended with the chief stating
urgently: "Go to the hospital. What seemed to be the gunshots were picked
up on Channel One during that interval.

       The NAS panel pointed out that Dallas County Sheriff Bill Decker
could be heard on both channels saying, "... Hold everything secure ...
seemingly about a half-second after the last gunshot on Channel One. Curry
had already told everyone on Channel Two a minute earlier to go to the
hospital. As a result, the Ramsey panel concluded that the supposed
gunshot noises came "too late to be attributed to assassination shots.

       What actually happened was that Curry issued his "go to the
hospital order right after the first shots were fired, wounding Kennedy
and Texas Gov. John Connally. The final bullet was fired in almost the
same instant that Curry uttered his command. A minute later, Decker,
riding in the same car with Curry, grabbed the mike and issued his orders
to "hold everything secure.

The study,s author said the chances that the National Academy of Science,s
single-gunman theory was correct were 1 in 100,000.

The NAS experts made several errors, Thomas said, but their
biggest mistake was in using Decker,s words to line up the two channels.
They ignored a much clearer instance of cross talk when Dallas police Sgt.
S. Q. Bellah can be heard on both channels, asking: "You want me to hold
this traffic on Stemmons until we find out something, or let it go?

       Those remarks come 179 seconds after the last gunshot on Channel
One and 180 seconds after Curry,s order to "go to the hospital on Channel
Two. When Bellah,s words are used to line up the two channels, Thomas
found, the gunshot sounds "occur at the exact instant that John F. Kennedy
was assassinated.

       How is it, then, that Decker,s remarks on Channel One come a full
minute after Curry,s on Channel Two and yet a half-second after the last
gunshot on Channel One?

       "It,s a misplaced bit of speech, Thomas said in an interview. "An
overdub. The recording needle for Channel One probably jumped. You can
hear Decker giving a whole set of instructions on Channel Two, but on
Channel One, you get only a fragment, ... hold everything secure. ... ,

       According to Thomas, the NAS panel made other mistakes: in
calculating the position of the grassy knoll shooter, in fixing the time
of that shot and in stating the Channel Two recorder had stopped when it
hadn,t. In all, Thomas said, the chances of the NAS panel having been
right were 1 in 100,000.

       House committee experts James Barger, Mark Weiss and Eric
Aschkenasy, have always held firm to their findings of a shot from the
knoll. Similarly, Ramsey, as chairman of the NAS panel, said last weekend
that he was "still fairly confident of his group,s work, but he said he
wanted to study the Science and Justice article before making further
comment. He said he did not recall the Bellah cross talk.


© 2001 The Washington Post Company