By David Willey
BBC News, Rome
On a fateful day in May 1981 at 1720 (1620 GMT), Ali Agca, a Turkish gunman, took aim and fired two pistol shots at the white-robed Pope as he was being driven around Saint Peter's Square in his Pope-mobile, greeting crowds of pilgrims.
The Pope forgave his would-be assassin, Mehmet Ali Agca
The Pope fell back into the arms of his devoted private secretary, seriously injured. He had a stomach wound and was bleeding profusely.
The Pope was rushed to hospital. The gunman was promptly arrested by Vatican gendarmes and handed over to Italian police.
News of the shooting caused a sensation as it sped around the world that evening. "Who would want to kill the Pope?", we kept asking ourselves.
The rapid identification of the Pope's would-be assassin was an even greater surprise. It turned out that Ali Agca, a member of a Turkish group of right-wing militants calling themselves The Grey Wolves had written an open letter to an Istanbul newspaper, threatening to kill the Pope when he visited Turkey in 1979.
The final truth about the shooting of the Pope remains as elusive as ever
I remember watching Ali Agca closely at his trial in Rome for attempted murder. He stood alone inside a cage in a heavily-fortified courtroom. He looked as if he was rather enjoying all the publicity. The guilty verdict and the life sentence were a foregone conclusion.
But Ali Agca turned out to be a model prisoner.
He wrote to the Pope, begging for forgiveness, and to his - and everyone else's surprise - the Pope went along two years later to the high-security jail where Agca was serving his sentence and spent some minutes alone with the man who had tried to kill him.
Agca did not act alone, the Pope later said
Years later, Pope John Paul recounted that during his private conversation with Agca, the gunman told him he couldn't understand how he had failed in his mission.
"I did everything according to plan, down to the smallest details," Agca told the Pope. But the Pope himself was confident he knew why Agca's designated victim had escaped death - divine intervention.
The Pope's actual words are revealing.
"Probably Agca understood that above the power to shoot and kill, there is a higher power," the Pope wrote reflectively, many years afterwards.
He presented the bullet that the surgeons had removed from his stomach to the shrine of the Virgin Mary at Fatima in Portugal. Encrusted in gold, the bullet now adorns a bejewelled crown placed on her statue.
The Pope also wrote that he knew his would-be assassin was a professional killer. The attempt was not his initiative: "Someone else planned and commissioned it," the Pope said, enigmatically.
Speculation about which country this might have been has remained just that - speculation. The former communist regimes of Eastern Europe have all fallen and many of the archives of their secret services have been open to researchers. But the final truth about the shooting of the Pope remains as elusive as ever.
A trial lasting 22 months was held in Rome during the 1980s about the alleged Bulgarian connection - involvement by the satellite state of the former Soviet Union. The accused were all acquitted for lack of proof.
The Russians have always maintained that the KGB wasn't responsible, even indirectly, although they would have had every reason to fear the international political fallout after the election of a Polish pope.
A Polish priest who was secretly spying inside the Vatican on behalf of Warsaw's communist government has only recently been unmasked.
One of the Italian judges who tried Agca says he fears for the safety of the Turk after his release from prison. Ali Agca now has grey hair and he is 48 years old. He knows too many secrets, the judge said.
The latest bizarre twist in this long-lasting mystery story is that Agca himself says he wants to return to Rome as soon as possible to meet John Paul's successor, Pope Benedict.