Vatican judges have refused to admit key evidence in the trial of the Pope's former butler, charged with stealing sensitive documents.
Paolo Gabriele's lawyers had asked to include evidence gathered by cardinals who carried out an inquiry into the "Vatileaks" scandal for Pope Benedict.
But judges at the high-profile trial said they would rely only on evidence from the Vatican police and prosecutor.
They adjourned the case until Tuesday, when Mr Gabriele will be questioned.
The 46-year-old admitted to investigators that he had leaked confidential documents to expose "evil and corruption".
He was identified as the source of leaked documents that were published in a book by an Italian journalist in May.
The documents included private correspondence between senior Vatican figures, and appeared to reveal bitter power struggles and corruption.
The Pope ordered cardinals to carry out an inquiry separate to the probe by Vatican police after the scandal broke.
The results of their investigation have not been made public.
Mr Gabriele faces up to four years in prison if convicted of aggravated theft, but he could be pardoned by the Pope.
The court decided that his fellow defendant, Vatican computer technician Claudio Sciarpelletti, will be tried separately for aiding and abetting a crime. He had exerted his right to stay away from the hearing.
Mr Gabriele was the Pope's trusted servant for years and held the keys to the papal apartments.
The BBC's David Willey in Rome says it has been one of the most difficult crises of Pope Benedict's seven-year papacy.
'Sadness to my heart'
No TV cameras or recorders are being allowed inside the courtroom for the most high-profile case to be held in the Vatican since it was established as a sovereign state in 1929.
Mr Gabriele, dressed in a pale grey suit, showed little reaction as judges rejected almost all of his lawyers' requests.
He will be interrogated in court by the president of the Vatican City tribunal on Tuesday.
The chief judge said the court hoped to reach a verdict by the end of next week.
Among witnesses due to give evidence next week is Pope Benedict's private secretary, Georg Gaenswein, and one of the six German and Italian nuns who work in the pope's private household.
The Vatican butler was arrested in May, accused of passing papal correspondence to journalist Gianluigi Nuzzi, whose book His Holiness: The secret papers of Pope Benedict XVI was published that month.
Correspondents say the revelations seem aimed primarily at discrediting the Vatican's powerful Secretary of State, Cardinal Tarcisio Bertone, who has been in his post since 2006.
Prosecutors quoted Mr Gabriele as saying during his interrogation that he knew taking the documents was wrong but he felt the Holy Spirit was inspiring him to shed light on the problems he saw around him.
He said he felt the Pope was being kept in the dark or misinformed by his collaborators.
Pope Benedict said after his former butler's arrest that the news had "brought sadness in my heart".