ROME (CNN) — Paolo Gabriele, former butler to Pope Benedict XVI, will take the stand in his own trial Tuesday to answer to criminal charges of stealing hundreds of secret papers from the pope's personal apartment and leaking them to an Italian journalist.
Corruption claims resulting from the publication of a book based on the leaked documents rocked the Catholic Church hierarchy and could even affect who becomes the next pope.
If convicted Gabriele could face up to eight years in an Italian prison, although it is possible the pontiff could choose to pardon him. He is accused of aggravated theft.
Gabriele has not entered a plea but did admit to the Vatican prosecutor that he leaked the papers, according to Vatican statements.
A Vatican legal expert, Cardinal Velasio De Paolis, in an interview published in Italian daily newspaper la Repubblica Sunday, said that popes in the past have typically granted pardons in the face of sincere confessions and repentance.
The case is thought to be the most significant ever heard in the Vatican City courthouse, which has handled mostly petty theft cases in the past.
Vatican computer technician Claudio Sciarpelletti, who worked in the Vatican's secretariat of state, also faces trial, accused of complicity in the crime. If found guilty, he faces a shorter prison term of only a few months.
Judge Giuseppe Dalla Torre has separated his trial from Gabriele's upon request from Sciarpelletti's lawyer, Gianluca Benedetti.
Gabriele appeared pale and largely expressionless in Saturday's first hearing, according to journalists in attendance. He was clean shaven and dressed in a light gray suit. None of his family attended.
Sciarpelletti did not appear in the initial hearing, but Benedetti declared his client's innocence on his behalf.
On Monday, the Vatican Information Service published two lists of witnesses to appear in the trials. The witnesses are as separate as the trials themselves - not one of them is set to take the stand in both cases.
Witnesses called in butler Gabriele's case include the pope's personal secretary Georg Gaenswein, attendant to the pope Cristina Cernetti and several police officers involved in the investigation.
Testifying in the trial of computer technician Sciarpelletti are Carlo Maria Polvani from the Vatican state department, Swiss Guard security chief William Kloter and two police officers.
Saturday's session was held under closely controlled conditions, with only a handful of approved reporters allowed to attend, who then were required to brief other journalists.
The admitted journalists were made to hand over their own pens in exchange for Vatican-issue ones in case any contained concealed listening devices.
They recounted that Vatican investigators had seized 82 boxes of evidence from Gabriele's apartments in Vatican City and Castel Gondolfo, a small town near Rome.
Authorities also uncovered in Gabriele's apartment in Vatican City a gold nugget and a check made out to Pope Benedict XVI for 100,000 euros as well as an original version of Virgil's Aeneid from 1581.
Gabriele's lawyer, Christiana Arru, filed several motions concerning the admissibility of evidence, including the results of a psychological exam conducted without the presence of his lawyer and footage gathered via a hidden camera.
The Vatican has previously said Gabriele cooperated with investigators and admits leaking the papers, which consisted of faxes, letters and memos, including some from a high-ranking church official expressing concerns about corruption within the Vatican.
A prosecutor in the case said in a report last month that Gabriele acted out of a desire to combat "evil and corruption everywhere in the Church."
"I was certain that a shock ... would have been healthy to bring the church back onto the right track," Gabriele is quoted as saying by the prosecutor, Nicola Piccardi.
The Vatican City State penal code for proceedings involving its citizens is based on the Italian penal code of the second half of the 19th century. Dalla Torre will lead the debate in the courthouse, located behind St. Peter's Basilica, and question the defendant directly.
Prison terms handed down by the court are served in the Italian prison system, under an agreement between the Vatican City State and Italy.
Gabriele was arrested in May, following a top-level Vatican investigation into how the pope's private documents appeared in the best-selling book "Sua Santita" ("His Holiness"), by Italian journalist Gianluigi Nuzzi.
The Vatican called the publication of his book "criminal" when it was released in Italian.