PHOENIX -- A secret society called the Illuminati has been a topic of conspiracy theorists for decades.

“The Illuminati do exist,” said attorney Jonathan Levy.

At the center of a murder mystery is a man by the name of Paul Marcinkus, who lived right here in the Valley. Marcinkus was once a Papal guard, Archbishop and President of the Vatican Bank, which is how he knew fellow Italian banker Roberto Calvir.

"They very well were the Illuminati, at least in Italy -- powerful people behind the scenes, operating in secrecy," said Levy, who has been in a legal battle with the Vatican for years.

In 1982, Calvi was found hanged from the Blackfriar's bridge in London. It was staged to look like a suicide. Calvi was connected to the disappearance of more than $1.2 billion, much of it belonging to the Vatican and the Illuminati. Eventually, five people were charged with his death in Rome.

Marcinkus was also indicted for Calvi’s murder, but he never had to answer for it. He eluded questioning with help from the Vatican, and he retired here to Sun City with full diplomatic immunity granted by the church, which means all attempts to extradite him were denied. He never spoke to reporters, investigators or members of his congregation at St. Clement of Rome in Sun City.

"I thought it was kind of tasteless the way people would come up to him in the sacristy and say, 'What really happened back then?'" said Paul Yoder, the church's choir instructor. "And he'd just kind of smile and change the subject."

The Phoenix Archdiocese refused to speak to 5 Investigates about Marcinkus; however, it did release a statement:

"Those priests who knew him in his retirement are not going to go on camera and speculate about rumor and innuendo that they know nothing about."

And so the mystery remains unsolved.

"I think (Marcinkus) was a true foot soldier of the church," Yoder said. "We stand a much better chance of finding out about the Kennedy assassination."