ROME (CNN) -- The Vatican has confirmed the arrest of a non-clerical staff member on suspicion of leaking confidential documents to an Italian journalist.
"A man, not a priest, is under arrest following the investigations that led the Vatican police to identify a person holding illegally private documents," Vatican spokesman Federico Lombardi told CNN in a telephone interview Friday.
Italy's ANSA news agency identified the man as 46-year-old Paolo Gabriele, the papal butler, who is one of only a handful of people with access to the pontiff's private desk.
Gabriele has worked for Pope Benedict since 2006 and his job included handing out rosaries to dignitaries and riding in the front seat of the "Popemobile," a vehicle used for public papal appearances, according to ANSA and evidenced in many photographs showing Gabriele with the pope.
Last month, the Vatican gave Cardinal Julian Herranz a "pontifical mandate" to uncover the source of hundreds of personal letters and confidential documents that have been released to Gianluigi Nuzzi, an Italian journalist and author of "Sua Santita" or "His Holiness" in which he published the documents.
Nuzzi would not confirm the identity of his sources, but he told CNN that his primary source, who he referred to as "Maria" in his book, "risked life and limb" if ever found out.
Nuzzi will not identify the gender or ages of his sources, but he told CNN that they worked inside the Vatican. He would not confirm if they were clergy or not.
Nuzzi told CNN that he has not been questioned in connection with the arrest. The Vatican called the publication of his book "criminal" when it was released last Saturday in Italian.
It has risen to number 1 in Italian book sales, according to Feltrenelli and Mondadori booksellers.
Nuzzi's book highlights an internal power struggle within the Vatican through numerous documents including faxes, personal letters and inter-Vatican memos.
Nuzzi told CNN that he received the documents during a year of private meetings in secret locations.
The documents show that the allegations of corruption and money laundering were a concern for a number of high ranking prelates, including Carlo Maria Vigano, who is now the Papal Nuncio in Washington, DC.
Vigano wrote in a series of letters to the pope that he was concerned about the spread of corruption and that his move to Washington would stir speculation.
"Holy Father, my transfer at this time would provoke much disorientation and discouragement in those who have believed it was possible to clean up so many situations of corruption and abuse of power that have been rooted in the management of so many departments," according to his letter which was published in the book.
The Vatican has not denied the authenticity of the documents, but instead says the breach of privacy is a criminal act.
The Vatican has its own judicial system, separate from the Italian judicial system.
The suspect is being held in a special cell within the Vatican City, a walled enclave within Rome, according to Lombardi.
There is no information about whether his legal defense will be from one of the Vatican's house lawyers, or if he will use the services of a lawyer outside the Vatican system.
Nicola Picardi, the Vatican's chief prosecutor, is leading the investigation, according to Lombardi. The pope is "saddened and shocked" at the arrest, he added.