Vatican police said they found about 1,000 confidential papers in the apartment of Pope Benedict's former butler, 46-year-old Paolo Gabriele - including some signed by the pope, and others by cardinals and politicians.
The papers - which Gabriele admits he photocopied and passed on at secret meetings - included letters to the pope in which a senior Vatican functionary expressed concern about improper behaviour in the Holy See's business dealings.
The leaks were a blow to the Vatican, which has been eager to clean up its image after a series of scandals involving its bank.
The letter-writer, Archbishop Carlo Maria Vigano, was later posted to Washington despite pleading to be allowed to remain at the papal state.
The case, dubbed "Vatileaks", saw the butler imprisoned in the Vatican police station while investigators seized 82 boxes of evidence from the apartment where he lived with his wife and three children. Of the hundreds of thousands of papers seized, about 1,000 were found to be of interest because they were original or photocopied Vatican documents.
Gabriele, an unassuming and devout servant who prompted a crisis in Benedict's papacy after he slipped sensitive documents to an Italian journalist, had stolen the documents hoping to expose corrupt dealings in the Vatican.
On Wednesday, the third day of Gabriele's trial for aggravated theft, Vatican gendarme Silvano Carli testified that the papers included "documents in code".
"There were many more documents than were published in the book," he said, referring to a book containing Gabriele's alleged leaks that was published by an Italian journalist.
Policeman Stefano de Santis told the court that some of the documents found but not considered of interest for the inquiry were about the suspicious death of Italian banker Roberto Calvi, dubbed "God's Banker", who was found hanging from Blackfriars bridge in London in 1982.
De Santis said there were also documents about using a concealed mobile phone and how to make videos as well as research on Berlusconi, Italian masonic lodges and research on "Christianity and Yoga, Buddhism and Yoga".
He said that during the search Gabriele had told investigators: "Have you seen how much I like reading? Have you seen how much I like studying?"
Some of the original documents, De Santis testified, carried the pope's handwriting with a note to destroy them written in German.
Allegations of mistreatment
Officer Luca Cintia, who took part in the search of Gabriele's apartment, responded to accusations by Gabriele that he had been mistreated during his detention, telling the court that he had been the main person in charge of the butler's detention.
He said Gabriele "was treated in the best possible way. He was treated with kid gloves. So much so that he thanked us".
Gabriele was held for 53 days following his arrest on May 23 in a Vatican security cell at the gendarmerie since the Vatican has no jail. He has since been placed under conditions of house arrest.
'Expected to confess'
Al Jazeera's Claudio Lavanga, reporting from the Vatican, said Gabriele is "expected to confess to the crime, because he has already done so to prosecutors during the pre-trial hearing".
Lavanga explained it is unclear "whether he's going to take all the blame as he's done until now, or whether he will reveal whether he was helped by anybody else - as the journalist who received the documents from him has said".
The man who helped the pope dress and rode in the front seat of the pope-mobile could now face up to four years in an Italian prison. Vatican spokesman Federico Lombardi said a verdict from the three-judge panel could be expected on Saturday after closing statements are made.