Agca has spent nearly 30 years in prison
The man who shot Pope John Paul II in 1981 has been set free after nearly 30 years behind bars.
But facts are few, and theories many, as to what Mehmet Ali Agca's motives might have been.
Born in 1958 in Malatya province in eastern Turkey, Agca was a member of street gangs and involved in petty crime in his youth.
He became a smuggler between Turkey and Bulgaria, and then went to Syria, where he says he received weaponry and terrorist training which he claimed was funded by Bulgaria.
In 1979, while part of a Turkish ultra-nationalistic group called the Grey Wolves, Agca killed Abdi Ipekci, a prominent newspaper editor.
While awaiting trial for that crime, he escaped from prison to Bulgaria and was sentenced in his absence.
He reappeared in St Peter's Square in the Vatican on 13 May 1981.
He opened fire on the Pope as he was being driven across the square in his open "Popemobile" to hold a general audience with a crowd of 20,000 people.
The conversation between the Pope and Agca remained a secret
The Pope was hit by three bullets, one of which entered his stomach. Two of his aides were also injured.
Agca was arrested by Italian police as he tried to flee and sentenced to life imprisonment in Italy in July 1981.
Two years later the Pope publicly forgave Agca and even visited him in the Rebibbia prison in Rome, meeting him for 20 minutes.
Their conversation was kept confidential.
Trials and investigations
But Agca's reasons for the shooting remained a mystery.
When first caught, he said he acted alone, but later made contradictory and often bizarre statements.
He said he was linked to a Palestinian militant group, but later blamed the Bulgarian secret service and the Soviet KGB for plotting the assassination attempt.
In court he claimed to be a new messiah, and questions were raised about his mental health.
In other statements he offered to team up with Dan Brown, the best-selling religious conspiracy writer, to produce a novel called The Vatican's Code.
He has also volunteered to go to Afghanistan to kill Osama Bin Laden, the leader of al-Qaeda.
The alleged link to Bulgarian and Soviet secret services was certainly plausible: part of a communist plot to kill the Pope, who helped loosen the grip of communist authorities in his native Poland.
But after three investigations and two trials, no link was ever proved.
However in his memoir, Memory and Identity, published in 2005, John Paul II himself wrote that he was convinced that the attempted assassination was planned and commissioned.
In June 2000, the Italian President Carlo Ciampi pardoned Agca, and he was extradited to Turkey to complete his prison sentence for the murder of Abdi Ipekci.
He was released in January 2006, and after a check-up at a military hospital was declared unfit for military service, because of "advanced anti-social personality disorder".
But after just eight days, he was rearrested, when the Turkish Supreme Court ruled that he had not spent enough time in jail for the killing of the Turkish journalist.
Now, as he tastes freedom after almost three decades behind bars, will the reasons behind his shooting of the Pope become clear?
He has promised, in a letter released by his lawyers, that he will answer questions about the attack, and says he is beginning to consider book, film and television documentary offers.
"We not running away from the media, he may speak in a few days," said his lawyer Gokay Gultekin.