Trial of Pope Benedict's former butler to start on Saturday VATICAN CITY (Reuters) - Pope Benedict's former butler, Paolo Gabriele, goes on trial on Saturday in one of the most embarrassing episodes in recent Vatican history. The trial of the 46-year-old man who served the pope his meals and helped him dress is due to start at 9:30 a.m. (4.30 p.m. EDT) in the Vatican's little-used tribunal, a small room with rich paneled wood and a papal emblem on its ceiling. His arrest on May 23 caused an international furor after police found confidential documents in his apartment inside the Vatican, a dramatic twist that threw the global media spotlight on an institution battling to defend its reputation from allegations of graft. A three-judge panel will decide the fate of Gabriele, whom the pope used to call "Paoletto" (little Paul) and who is now described in Vatican documents as "the defendant." Gabriele stands accused of stealing the pontiff's personal papers and leaking them to the media in what he says was an attempt to clean up corruption at the headquarters of the Roman Catholic Church. According to an indictment last August, Gabriele told investigators he had acted because he saw "evil and corruption everywhere in the Church" and wanted to help root it out "because the pope was not sufficiently informed." The documents pointed to a power struggle at the Church's highest levels. Gabriele, who said he saw himself as a whistle-blowing "agent of the Holy Spirit," is widely expected to be convicted on charges of aggravated theft because he has confessed. The trial procedures will be based on a 19th century Italian penal code and could result in a prison sentence of up to four years for Gabriele and one year for Claudio Sciarpelletti, a computer expert charged with aiding and abetting him. It is not clear how long the trial might last. Gabriele, a father of three who lived a simple but comfortable life in the city-state, told investigators after his arrest in May that he believed a shock "could be a healthy thing to bring the Church back on the right track." His arrest capped nearly five months of intrigue and suspense after a string of documents and private letters found their way into the Italian media. The most notorious of the letters were written to the pope by Archbishop Carlo Maria Vigano, currently the Vatican's ambassador to Washington, who was deputy governor of Vatican City at the time. Despite begging not to be moved away from the Vatican, Vigano was later transferred to Washington by Secretary of State Cardinal Tarcisio Bertone. Since the papal state has no prison, Gabriele would serve time in an Italian jail, though the pope is widely expected to pardon him. Reporting By Philip Pullella; Editing by Andrew Osborn