Gregory Adams, 34, a King of Prussia native, said he had read "just about everything in print" about the assassination, including High Treason, during the last 20 years.
"Where he's coming from is legitimate. I agree with his conclusions," Adams said.
High Treason, published in May 1989, was the culmination of 14 years of investigative work by Groden, a photo-optics technician who was a photographic consultant in the mid-1970s to the House Assassinations Committee, and Baltimore writer Harrison Livingstone, who co-wrote the work.
The two men, both devotees of the case early on, researched volumes of material and interviewed dozens of witnesses for the book, which, rather than being built around a particular theory, Groden said, "includes all the evidence and shows where it leads."
In Groden's view, the evidence leads to a coup d'etat in which forces in the military-industrial establishment orchestrated Kennedy's death and the government covered it up with the Warren Commission report.
American intelligence forces, the Mafia and right-wing extremists are all implicated in the murder, he said.
The so-called conspiracy theory is not new.
Despite the authors' exhaustive research, deals with four major publishing firms fell through in part because the companies wanted to omit material, Groden said. The dispute forced Livingstone to print the book with his own small literary press, Conservatory Press.
Since the book's publication, Groden has been deluged with requests from radio and television talk shows - an indication of how interest in the assassination refuses to flag, even 27 years after the fact.
According to Groden, High Treason has sold 60,000 copies, and nearly 10,000 more are on order.
Why the public passion for the JFK murder? Is it merely the cloak-and- dagger elements of what one magazine editor called "the detective story of the century?"
No, Groden said, it is the search for the truth in the case.
For skeptics of the conspiracy theory, the truth is contained in the Warren
Commission report, the official government account of the murder released in 1964.
Professor Thomas Heston, chairman of the history department at West Chester University, is among those who say that a conspiracy and cover-up are ''unlikely."
"In order for there to have been an effective cover-up, thousands of people would have to have cooperated," he said.
Heston attributes conspiracy theories to "something in the American psyche."
"Whenever bad things happen, we think it must be a conspiracy," he said.
Heston said individuals brought their own "preconceived ideas and their own history" to any reading of historical events, "whether it's the assassination of Kennedy or the Reformation." This gives rise to a wide range of interpretations, he said.
"History is not provable the way science is," Heston said.
Groden, however, said the evidence spoke for itself.
As one of the people instrumental in getting the case reopened in 1975 by televising his enhancement of the Zapruder film - a home movie shot by an onlooker that day in Dallas - Groden provides what he considers an insider's view of the case.
In High Treason, he and Livingstone give their interpretations - some of them at variance with the Warren Commission findings - of testimony from witnesses in the case, post-mortem photographs of Kennedy, information about events surrounding the murder and a catalogue of mysterious deaths associated with it.
According to Groden, much of the evidence is scientific: acoustical tests, the film, autopsy photographs and X-rays, ballistics tests and more. And ''more and more evidence is coming forward all the time," he said.
Groden hopes that if Americans can review the details of the murder, they may pressure the government to take another look at the case.
"We need to find a congressman to reopen this, or possibly the Texas State Attorney General's Office," he said.
Groden, a tall, dark-haired man who appears somewhat shy, bookish, and younger than his 44 years, has spent more than a quarter of a century intrigued by the mystery of Kennedy's death. He says he has spent more than $50,000 of his money on his efforts.
His wife and four children have been supportive, even though he often has been an absentee family member, he said.
Groden's home is devoid of JFK icons. No pictures or framed quotations adorn the walls. It takes some searching to locate the bust of Kennedy perched high on a bookshelf in the corner of the living room. More prominent are the tools of Groden's endeavors: a television, a videocassette recorder, videocassette tapes, books - and two telephones that never stop ringing.
The avocation that now has become his full-time job began the day JFK was shot - Groden's 18th birthday.
"I admired President Kennedy. He was a man who tried to make the American
Dream a reality for all Americans," he said.
He said his suspicions about a cover-up arose shortly after the report of the Warren Commission - named for its chairman, then-Chief Justice Earl Warren - was released. After reading criticisms of the report, he said, he concluded ''it didn't hold water."
The Warren Commission concluded that Kennedy and Texas Gov. John Connally were struck by two bullets that were fired from behind by a single gunman - Lee Harvey Oswald. One of the bullets, the report said, killed the president.
In 1966, Groden obtained a copy of the unreleased Zapruder film - then the property of Time Inc. - and became convinced the case needed more investigation. He will not reveal how he got the film.
Never shown in its entirety, the film contained what he considered some telling details about the murder. By slowing down and enhancing the film, Groden said he was able to pinpoint in key frames the sequence of events when the shots started.
Kennedy is seen grabbing at his throat and seconds later being whipped back by a shot that appears to strike the front of the head. A subsequent frame shows what appears to be Kennedy's right temple being split open and the back of his head opening up upon the bullet's exit.
Groden put the film in a bank vault, fearing that going public might bring him trouble.
Groden finally went public with the film in 1975, when he appeared first at a Boston symposium on the assassination and then on the TV news. After a subsequent television appearance - on Geraldo Rivera's Goodnight America - he took his evidence to Washington, where U.S. Rep. Thomas Downing of Virginia called for a new investigation.
"I always had a question in my mind" about the Warren Commission report, Downing said in a recent telephone interview from his Virginia law office. ''Now I was utterly convinced that something was wrong."
When the House Assassinations Committee was formed, with Downing as chairman (he stepped down when he retired from the House midway through the investigation), Groden was appointed as a photographic consultant.
On the basis of the film, acoustics tests of a police tape that recorded Kennedy's motorcade and other research, the committee determined that at least three gunmen fired at least four shots into Dealey Plaza. The committee, however, stopped short of saying who the gunmen were or whom they were working for.
As photographic consultant, Groden examined autopsy photos that he thinks were faked with the use of matte insertion - the process of blending part of one photo into another. He said that one photograph of Kennedy's head, when enlarged, showed a marked contrast between the center and the outer area of the head.
"Whenever you do a matte insert, you have to match the overlay so the contrast stays the same," he said.
Groden said he was further convinced that the photos were fake when he heard the claims of medical professionals who treated Kennedy at Parkland Memorial Hospital. The doctors and nurses, interviewed on videotape and in the book, are quoted as saying the back of Kennedy's head bore a gaping, fist- sized exit wound. X-ray technicians and an autopsy photographer named in the book are quoted as saying the same thing. Their statements strongly suggest that Kennedy was struck by a bullet from the front.
In addition, the X-rays of the president's head did not match the photographs. That claim is backed up in a book by Robert McClelland, a doctor who treated Kennedy at Parkland, Groden said.
If the claims of doctors and nurses would have established immediately that Kennedy was shot from the front and back, then why didn't they testify as much?
They did, Groden said. But several key questions, such as those concerning the exit wound, were not asked, he said. Why? Because the pressure was on the
commission to "stop the conspiracy theory," he said.
The commission's report said Oswald shot three bullets from the Texas School Book Depository - one bullet missed, one hit Kennedy in the back of the head, and one went through Kennedy's back and out his throat, then through Connally's chest, wrist and thigh. The bullet, which authorities said they found in the hospital, was in remarkably good shape for having gone through two bodies.
This so-called single-bullet theory - labeled by skeptics as the "magic" bullet theory - was devised by U.S. Sen. Arlen Specter, who was then a young Philadelphia lawyer and counsel to the commission.
Based on the Zapruder film and sound analyses of the police tape, Groden concluded that at least seven shots were fired from a possible six locations, with the fatal head shot coming from the so-called grassy knoll in front of the motorcade.
In the book, a photograph enlarged by Groden shows someone standing in the off-limits area behind the fence on the knoll before the assassination.
Perhaps one of the strongest arguments against the theory that Oswald killed Kennedy is the fact that the Mannlicher-Carcano rifle allegedly used by Oswald is incapable of firing shots quicker than 2.3 seconds apart, Groden said. The acoustics tests and the Zapruder film indicate that at least two shots were fired less than two seconds apart.
Most likely, Oswald, reportedly a low-level operative for the CIA, never fired a shot that day in Dallas, but was instead a convenient patsy, Groden said.
As part of the conspiracy evidence, the authors have included excerpts of transcribed FBI tapes - released under the Freedom of Information Act - that hint at the involvement of right-wing extremists.
They also cite various articles that point to the CIA's activities in Cuba after the Castro takeover, and how the agency was miffed at Kennedy's decision not to topple the Cuban leader.
In addition, they contend that Kennedy made a declaration to withdraw military advisers from Vietnam, upsetting industrial barons set on a war that eventually netted industry $220 billion.
When viewed as parts of a puzzle, Groden said, the evidence forms an inescapable conclusion of a conspiracy.
Specter would not return phone calls. His press secretary, Dan McKenna, said, however, that Specter did not read books about the assassination and
rarely responded to charges against the Warren Commission report.
"These theories go on and on," McKenna said. "It's just never going to be resolved."
Groden maintains that the case could be resolved with a new inquiry.
"I'm not dogmatic about any of the evidence," Groden said. "If Lee Harvey Oswald did it, and did it alone, then so be it and let's see the proof."