ROME — A mysterious source named Maria. A room furnished with a single chair, where sensitive Vatican documents are turned over to an investigative journalist at regular meetings. The arrest of the pope’s butler. Perhaps the greatest breach in centuries in the wall of secrecy that surrounds the Vatican.

An on-again, off-again scandal that the Italian press has called VatiLeaks burst into the open Friday with the arrest by Vatican gendarmes of a man, identified in news reports as Paolo Gabriele, the pope’s butler, who the Vatican said was in possession of confidential documents and was suspected of leaking private letters, some of which were addressed to Pope Benedict XVI.

The arrest follows by a day the ouster of the president of the Vatican Bank, Ettore Gotti Tedeschi, amid conflicts over how to bring the secretive institution in line with international transparency standards and days after the publication of a sensational book, “Your Holiness: The Secret Papers of Benedict XVI,” in which the journalist Gianluigi Nuzzi, aided by “Maria,” discloses a huge cache of private Vatican correspondence, many with allegations of mismanagement at the Vatican bank and cases of corruption and cronyism.

The letters, which have made their way into the Italian news media in recent months, draw a portrait of an ancient institution in chaotic disarray behind its high, stately walls, where various factions vie for power, influence and financial control in the twilight years of Benedict’s papacy.

“Of course there are problems, big problems,” said Andrea Tornielli, a Vatican expert for the Italian daily La Stampa and its website, Vatican Insider. “What is happening now shows that there’s a crisis.”

It was not clear whether the bank president’s ouster and the arrest of the man found with confidential documents were directly related, although Nuzzi’s book includes various memos from Gotti Tedeschi about the Vatican bank.

The Vatican spokesman, the Rev. Federico Lombardi, declined to identify the person who was arrested, saying only that he was not a priest or member of a religious order and that he had been detained for further investigation.

But Italian news media reported that he was Gabriele, 40, and a butler in the papal household. Some publications even showed images of him holding a white umbrella above the pope and pouring him wine at dinner.

The twist that “the butler did it” was fully worthy of a whodunit that began earlier this year when documents began appearing in the Italian press. In one, a Sicilian cardinal, writing in German in order to be more stealthy, said he had heard in China about a bizarre plot to kill the pope. At the time, Lombardi called the accounts “delirious and incomprehensible.”

In another letter from 2011 that appeared in the Italian press this year and is also published in Nuzzi’s book, Archbishop Carlo Maria Vigano, then the deputy governor of Vatican City, wrote directly to Benedict. In it, he argued that transferring him to another post would impede his efforts to fight “corruption and abuse” in various Vatican offices, sending the wrong signal about his efforts to rein in cronyism in the awarding of contracts for construction work at the Vatican.