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Pope Benedict continued with his programme on Sunday (May 27) conducting the Pentecostal Mass in St. Peter's Basilica. The Pope looked pensive at times during the mass and whilst the major part of his homily dealt with Pentecost, he did add some words at the end which might allude to the intensive investigation being carried out in Vatican City following the arrest of his personal butler.

"Dear friends, we must live by the spirit of unity and truth, and for this we must pray for the spirit to enlighten and guide us to follow our truth, and to accept the truth of Christ transmitted in the Church, " said Pope Benedict during his homily for Pentecost.

Vatican magistrates formally charged Pope Benedict's butler with illegal possession of secret documents on Saturday (May 26) and said a wider investigation would take place to see if he had any accomplices who helped him leak them.

Paolo Gabriele is suspected of leaking highly sensitive documents, some alleging cronyism and corruption in Vatican contracts, in a scandal which has come to be known as "Vatileaks".

A statement referred to Gabriele, 46, who was until his arrest on Wednesday night serving the pope meals and helping him dress, as "the defendant". It said a preliminary investigation had been upgraded to a "formal investigation," meaning he had been formally charged, and had chosen two lawyers to defend him. Because the Vatican has no jail, 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.

The Vatican promised that he would have "all the juridical guarantees foreseen by the criminal code of the State of Vatican City." The Vatican 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.

Commentators in Italian newspapers 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.

The scandal involves the leaking of a string of documents to Italian media in January and February, including personal letters to the pope.