For someone at the center of one of the Vatican's greatest scandals in recent decades, Gianluigi Nuzzi seems awfully cool.

The investigative journalist who published a book of leaked papal documents begs to get off the phone one day because he's playing with his two kids at home in Milan. A day later he's ensconced in a swank hotel on Rome's Via Veneto, joking about cutting his journalistic chops as a 13-year-old writing for a weekly Mickey Mouse magazine.

But Nuzzi, 42, is very much in the hot seat for revealing the secrets of one of the most secretive institutions in the world, accused of an unprecedented attack on both the pope and the Catholic Church.

"His Holiness: The Secret Papers of Benedict XVI" was published last week. In the few days since, it has become the most-talked about book in Italy and the Vatican, 273 pages of leaked Holy See documents and analysis of the Vatican's internal machinery that represents its biggest security breach in recent history.

The documents expose episodes of political infighting, intrigue and accusations of corruption and homosexual liaisons going on under the watch of the 85-year-old Benedict. Taken together with other leaks that have emerged in the Italian press in recent months, they paint a picture of a Catholic Church hierarchy in utter disarray.

The papers include letters to the pope and his private secretary, bank statements, a handwritten memo the pope's personal secretary wrote in his native German about a meeting with a member of the disgraced Legion of Christ.

None of the documents represents a smoking gun that will bring down the papacy. Most are of interest only to Italians, as they concern relations between Italy and the Vatican and a few local scandals and personalities. But their very existence and the fact that they were taken from the pope's own desk has provoked an unprecedented reaction from the Vatican. A criminal probe, a high-level internal investigation and administrative whodunit is under way, and Nuzzi has been put on notice that legal action is pending.

Nuzzi, who as a child used to ring the church bells at his local parish, is unfazed.

Asked Wednesday how he was doing, Nuzzi smiled and says he's living "with the serenity of someone who did his job, who found news and made it public."

"This is news," he said of his book, and then revealed news of his own about his sources. "We have a group of people _ I can count more than 10 _ who decided to make things public. When they made this choice months ago, I think and believe they were perfectly aware of what would happen."

So far only one person has been arrested in the scandal: Paolo Gabriele, the pope's personal butler, who was taken into custody by Vatican security last week after a trove of Benedict's documents were found in his Vatican City apartment.

The arrest gave the scandal an unfathomable Dan Brown twist: the pope's trusted butler, a citizen and employee of the Vatican city state, a devout 46-year-old father of three accused of stealing the pope's secret papers.

But few believe that Gabriele acted alone and he has promised to cooperate with the investigation, suggesting that other heads may roll.

Unless he is a very good actor, Nuzzi's demeanor implied that the butler actually didn't do it. The author stumbled when he pronounced Gabriele's last name and seemed to genuinely ache for a fellow father of young children who was deprived of his freedom.

In an interview with The Associated Press, Nuzzi said he had spoken to his key source _ identified only by the code name "Maria" _ since the whirlwind erupted and said the source projected "an absolute serenity" about what was transpiring.

Benedict on Wednesday broke his silence about the case, saying in his general audience that the turmoil of recent days had "brought sadness to my heart." But he added that he renewed his trust and faith in his assistants who "every day, with loyalty and a spirit of sacrifice and in silence, help me fulfill my ministry."

A day earlier, the No. 2 in the Vatican secretariat of state, Archbishop Angelo Becciu, accused those responsible of an unprecedented "brutal" attack on the pope, saying the stolen papers didn't just concern matters of internal church governance but represented the thoughts of people who in writing to the pope believed they were essentially speaking before God.

Nuzzi acknowledged the sentiments, but has stressed that the documents weren't private papers so much as documentation about relations between states and issues of interest to the public _ data that his sources risked their livelihoods to expose because they couldn't bear to keep them secret.

"I understand the pain that this news has caused. And I respect the pain and also people's anger," he said. "Just as I understand the pain of these people who were living with these issues _ secrets that they just couldn't endure."

The motivations for the leaks remain unclear: Some commentators say they appear designed to discredit Benedict's No. 2, the Vatican secretary of state, Cardinal Tarcisio Bertone. Others say they're aimed at undermining the Vatican's efforts to become more financially transparent. Still others say they aim to show Benedict's weakness in running the church. Continued...