Challenge to lone gunman theoryby Betty Mason, Contra Costa Times - August 20, 2006
LIVERMORE More than four decades after his death, John F. Kennedy's assassination remains the hottest cold case in U.S. history, and the clues continue to trickle in. Now Lawrence Livermore Laboratory scientists say a key piece of evidence supporting the lone gunman theory should be thrown out.
A new look at clues gleaned from studies of crime-scene bullet fragments shows they may have been misinterpreted.
"It basically shatters what some people call the best physical evidence around," said chemist Pat Grant, director of the lab's Forensic Science Center.
Grant and Livermore Lab metallurgist Erik Randich found that the chemical "fingerprints" used to identify which bullets the fragments came from are actually more like run-of-the-mill tire tracks than one-of-a-kind fingerprints.
"I've spoken with people on both sides of the conspiracy divide and there's no question but that (Randich and Grant's) work is going to be very difficult, if not outright impossible, to refute," said Gary Aguilar, a San Francisco ophthalmologist and single-bullet skeptic who has studied the Kennedy assassination for more than a decade. "It looks impregnable."
The government's claim that Lee Harvey Oswald alone killed Kennedy spawned a vitriolic debate between conspiracy theorists and lone gunman supporters that rages to this day.
In 1964, the Warren Commission, established by President Lyndon B. Johnson to investigate the assassination, concluded that Oswald fired just three shots from the Texas School Book Depository in Dallas: The first missed entirely. The second passed through the president's neck, into Texas Governor John Connally's body under his right arm, out through his chest and then splintered his wrist and wounded his left thigh. The third fatally hit Kennedy in the head.
Even though three bullets were involved, this scenario became known as the "single-bullet theory" because it requires the second bullet to account for all the nonfatal injuries to both Kennedy and Connally.
The injuries to Kennedy's neck and to Connally happened within a split second of each other. So either the injuries to both men came from a single bullet from Oswald or from at least two bullets from more than one shooter. Oswald's rifle couldn't have fired two shots in such rapid succession.
So in order for Oswald to be the lone gunman, it had to be a single bullet.
Skeptics and believers alike say the bullets amount to the most important piece of physical evidence for the single-bullet theory. Throwing it out is like removing a leg from a four-legged table.
"Warren Commission defenders consider this evidence central to the single-bullet theory," Aguilar said.
But Grant and Randich say the bullet lead analysis was faulty. Both Randich and Grant are forensic scientists at Livermore Lab but researched the JFK case on their own time. Their work is the latest chapter in an ongoing saga.
In the immediate aftermath of the assassination, the FBI analyzed five bullet fragments recovered from the limousine, the governor's wrist, the president's brain and from a hospital stretcher.
The FBI used a technique known as "neutron activation" analysis to find the precise composition of the fragments. By determining the exact amounts of impurities in the lead, such as antimony and silver, they hoped to be able to tell which fragments came from the same bullet. But the FBI decided it couldn't draw any conclusions from the results.
In 1976, the U.S. House of Representatives formed an assassination committee to investigate the deaths of JFK and Martin Luther King Jr. The move was largely a response to hundreds of books, documentaries and magazine pieces questioning the government's version of the JFK assassination, as well as public outcry following the first airing of Abraham Zapruder's home movie of the assassination on the television show, "Good Night America."
The committee called in nuclear chemist Vincent Guinn, one of the world's foremost experts on neutron activation, to reanalyze the bits of bullet lead.
Unlike the FBI, Guinn drew a very clear conclusion. He said the antimony in the fragments clearly showed they all came from two, and only two, bullets of the type used by Oswald's gun, which supports the Warren Commission's lone gunman theory.
According to Guinn, one set of fragments from the president's brain and the limousine in front of the president had around .06 percent antimony, and all came from the bullet that killed JFK. The other set of fragments from the governor's wrist and a nearly intact bullet found on a stretcher at the hospital had closer to .08 percent antimony and were pieces of the infamous "single bullet."
Based on evidence including the bullet lead, the committee concluded in 1979 that both shots had come from Oswald's gun.
They did not, however, rule out the possibility of a conspiracy. In fact, they strongly suspected a second shooter was present that day, but based on Guinn's data, any second shooter had missed the target.
Or maybe not.
"It turns out that if you really analyze the results correctly, then the results are wrong," said Grant.
Randich and Grant's study grew out of work Randich did in 2002 that exposed a fatal flaw in the FBI's use of bullet-lead evidence to connect suspects with crime scenes in thousands of criminal cases during the past three decades.
The FBI claimed that like a fingerprint, each batch of lead has a unique chemical signature, so the specific amounts of impurities in a lead bullet could match it with other bullets from the same batch. For example, if bullets at a suspect's house were found to have the same impurity signature as a bullet or fragment found at a murder scene, it was treated as evidence tying the suspect to the crime.
Randich's training as a metallurgist told him there was something wrong with this reasoning.
"I realized these people could put my sons in jail with bogus science," he said. "I thought I ought to do something about it."
By analyzing years of data kept by lead smelters, Randich found that batches are not unique, and bullets from different batches of bullets poured months or years apart could have the same chemical signature. And bullets poured from the start of a batch could differ slightly, but measurably, from those at the end.
He has testified in about a dozen cases. Because of his work, courts now reject bullet-lead analysis and the FBI no longer uses it as evidence.
JFK case problems
The JFK case has similar problems.
According to Guinn, the type of bullets used by Oswald happened to have highly variable amounts of antimony.
Guinn said the variation between bullets of this type was so great that he could use it to tell individual bullets apart, even from the same batch of lead.
Randich and Grant say that assumption is dead wrong.
They analyzed the same type of bullets and showed that within a single bullet, there is a significant variation in impurities on a microscopic scale. The range of concentrations of impurities in each bullet is large enough to make small fragments from different parts of the same bullet have very different chemical fingerprints.
Some of the fragments in the JFK case are so small that the differences in antimony could be explained entirely by this microscopic variation, instead of by differences between bullets, they said. Randich and Grant's study was published in July in the Journal of Forensic Sciences.
One to five bullets
"We don't know if there were two bullets," said Randich. "There could have been two bullets, but the lead composition data shows there could be anywhere from one to five bullets."
The bullet found on the stretcher is missing some lead, but not enough to account for all the other fragments. So there had to be more than one bullet. But Grant and Randich say there is no way to tell how many more, at least from the bullet lead.
Losing Guinn's bullet-lead evidence is a major blow to the single-bullet theory.
That evidence "knits together the core physical evidence into an airtight case against Lee Oswald," according to a 2004 paper by Larry Sturdivan and Ken Rahn in an issue of Journal of Radioanalytical and Nuclear Chemistry that celebrated Vincent Guinn after his death. "It is, thus, the key to resolving the major controversies in the JFK assassination and putting the matter to rest," the paper said.
Rahn, an atmospheric chemist recently retired from the University of Rhode Island, stands by this statement and Guinn's research despite Randich and Grant's study.
He says he believes it is possible that microscopic variation occurs within bullets of this type, but Grant and Randich can't say for sure whether it happened in the JFK bullets because they didn't analyze those particular fragments.
Rahn thinks it is far more likely the fragments fell into two distinct groups, one with .06 percent antimony and the other with .08 percent, because they came from two distinct bullets.
This fits the Warren Commission's conclusion that Oswald was the lone shooter, and two of the three bullets he shot hit the occupants of the president's limousine, Rahn said.
Grant counters that the two groups of bullet fragments might not actually be that distinct. The margin of error associated with the antimony analysis means that, statistically, the concentrations are too close to separate into groups.
Although Randich and Grant's research doesn't solve the Kennedy assassination, it certainly does weaken the case for a lone gunman.
"In recent years, the (bullet) fragment evidence has become one of the key struts supporting the single-bullet theory," Aguilar said. "Randich and Grant have knocked this slat out from under the theory."
Betsy Mason covers science and the national laboratories. Reach her at email@example.com or 925-847-2158.
|Home Author Articles Archives Links|
click on the whale to send email