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 on 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 revealing clashes over the management at the Vatican bank and allegations 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.