James Fetzer, author of "Assassination Science: Experts Speak Out on the Death of JFK," says the Kennedy X-rays and the film of the assassination by bystander Abraham Zapruder were fabricated and that there were actually six or so people firing at the president that day.

"The driver actually brought the limo to a halt to make sure Kennedy was hit enough times to be killed. The Secret Service set him up, and we have more than 15 indications of them doing that," Fetzer said. "The order of vehicles in the motorcade were wrong, that's perhaps the most telling. Nixon knew about it, too. J. Edgar Hoover and LBJ were involved as well, I'm sorry to say."

In 1967, New Orleans District Attorney Jim Garrison asserted that the assassination was a CIA-led coup. Garrison's theories went to court — and eventually to Hollywood as Oliver Stone's 1991 movie "JFK" — but Clay Shaw, the alleged "evil genius" behind the assassination, was acquitted in less than an hour.

Technology has only solidified positions.

Conspiracy theorists now use the Internet to bounce their ideas around the globe, build databases and convert a new generation of believers.

ABC and Court TV both ran sophisticated computer simulations this month of the crime scene and an analysis of a police audiotape, asserting that the Warren Commission got it right — Oswald alone killed Kennedy.

The now-digitized Zapruder film shows exact moments — such as the second when Connally's lapel flew up — that indicate precisely when he was shot and his position relative to the president. Their conclusion: Connally, who sat in front of Kennedy, was turning when he was shot, making the bullet's path plausible.

Many Americans nevertheless find it difficult to believe that a nobody like Oswald — a former Marine who went to live in Russia, became disenchanted with life under communism, and took a dead-end job in Texas — could have single-handedly killed the leader of the free world.

Some 6 million documents have been released by the Assassination Records Review Board, but Kermit Hall, president of Utah State University and one of five people on the board, said he doubts any revelations will come from them.

"The lesson of American history is, by and large, unhappy small-time people, if you will, make more of their life by shooting or killing-better known people," Hall said.