Pope Benedict XVI's butler has been arrested and charged with illegal possession of secret documents following embarrassing leaks that exposed alleged intrigue and corruption in the Vatican, a spokesman has said.
Federico Lombardi said in a statement on Saturday that Paolo Gabriele, a layman who lives inside Vatican City, was arrested on Wednesday.
The Vatican said a wider investigation would take place to see if Gabriele, 46, had any accomplices that helped him leak the documents.
Vatican documents leaked to the press in recent months alleged corruption in Vatican finance and bickering over the Holy See's efforts to show more transparency in its financial operations.
Italian commentators said they doubted that Gabriele could have acted alone and some speculated that he may have been a pawn in a larger, internal power struggle.
"Never has the sense of disorientation in the Catholic Church reached these levels," Church historian Alberto Melloni wrote in Italy's Corriere della Sera newspaper. "But now there is something even more - a sense of systemic disorder."
A statement referred to Gabriele, who was until his arrest serving the pope meals and helping him dress, as "the defendant".
Gabriele was being held in one of the three so-called "secure rooms" in the offices of the Vatican's tiny police force inside the walled city-state as the Vatican has no jail.
The Vatican promised that he would have "all the juridical guarantees foreseen by the criminal code of the State of Vatican City".
It said the upgraded, formal investigation "would continue until a sufficient framework of the situation is acquired", which a Vatican official said meant magistrates wanted to determine if Gabriele acted alone or with others.
The pope was said to be "pained" that someone in his domestic household had betrayed him. Gabriele lived in the Vatican with his wife and three children.
He has been close to the pope, often seen by his side in public and riding in the front seat of the pontiff's open-air jeep during the pope's general audiences.
The scandal, dubbed "Vatileaks", has seriously embarrassed the Vatican, at a time it is trying to show the world financial community that it has shed its reputation as a scandal-plagued tax haven.
At the centre of the scandal is Pope Benedict XVI's No 2, Cardinal Tarcisio Bertone, the Vatican secretary of state.
The scandal took on even greater weight last week with the publication of "His Holiness", a book which reproduced confidential letters and memos to and from Benedict and his personal secretary.
The Vatican called the book "criminal" and vowed to take legal action against the author, publisher, and whoever leaked the documents.
The Vatican had already warned of legal action against the author, Italian journalist Gianluigi Nuzzi, after he broadcast letters in January from the former No 2 Vatican administrator to the pope in which he begged not to be transferred for having exposed alleged corruption that cost the Holy See millions of euros in higher contract prices.
The prelate, Monsignor Carlo Maria Vigano, is now the Vatican's US ambassador.
Nuzzi, author of "Vatican SpA", a 2009 volume laying out shady dealings of the Vatican bank based on leaked documents, said he was approached by sources inside the Vatican with the trove of new documents.
Most of them, he said, were of fairly recent vintage and many of them painted Bertone in a negative light.