(Repeats Sunday story with no changes)
* Friend of former butler charged with aiding and abetting
* Trial in Vatican tribunal expected to be very quick
* Computer expert gave conflicting versions when questioned
* Butler Gabriele serving 18 months for aggravated theft
VATICAN CITY, Nov 4 (Reuters) - A Vatican computer expert goes before a court on Monday in a trial that could shed light on whether Pope Benedict's former butler acted alone in leaking sensitive documents or was a pawn in a bigger power struggle.
Claudio Sciarpelletti is accused of aiding and abetting the butler, Paolo Gabriele, who in October was sentenced to 18 months in jail for aggravated theft.
Sciarpelletti, 48, spent one night in a Vatican jail cell on May 25, two days after Gabriele was arrested when police searched his home and found many copies of papal documents, some alleging infighting in the papal court and corruption at the highest levels of the Roman Catholic Church.
Gabriele, one of the pope's closest household assistants, admitted leaking the documents to the media in what he said was an attempt to help disclose corruption and "evil" in the headquarters of the 1.2 billion-member faith.
Vatican officials, eager to put the embarrassing episode behind them, say Sciarpelletti's role was marginal and expect the trial, in the same small court room, to be speedier than that of the ex butler, which lasted only four sessions.
When Vatican police searched Sciarpelletti's desk in the Secretariat of State - the nerve centre of the Holy See's administration - they found a closed envelope addressed to Gabriele and marked "personal".
It contained documentation relating to a chapter in a book about Vatican corruption and intrigue written by Italian journalist Gianluigi Nuzzi, who received confidential documents from Gabriele.
In four sessions of questioning in May and June, Sciarpelletti provided "wavering and contradictory" answers, according to a court indictment.
On the night of his arrest, Sciarpelletti said he had just a "working relationship with Gabriele. He later said the two were friends and their families had gone on outings together and that he knew that Gabriele had had a very difficult childhood.
Sciarpelletti at first said Gabriele gave him the envelope. He later said it had been given to him by someone in the Vatican identified only as "W" in court documents and later said it had been given to him by someone identified as "X".
It is not clear if X or W are clerics or lay people working in the Vatican.
Prosecutors had at first considered charging Sciarpelletti with being a direct accomplice to aggravated theft, violation of state secrecy and obstruction of justice but later lessened their accusations to aiding and abetting.
Among the witness expected to be called are Gabriele, Monsignor Carlo Polvani, Sciarpelletti's superior in the Secretariat of State, Major William Kloter, the deputy commander of the Swiss Guards, and two Vatican security officials, including the commander of the police force, Domenico Giani.
Sciarpelletti faces up to one year in jail but is expected to get off with a light sentence or a fine.
At the end of Gabriele's trial some commentators faulted the judge for not pursuing other lines of questioning regarding who "influenced" the butler, leaving many doubts and suspicions lingering.
The documents he leaked constituted one of the biggest crises of Pope Benedict's papacy, embarrassing the Vatican as it struggled to overcome a string of child sex abuse scandals involving clerics and mismanagement at its bank.
Gabriele told investigators he had acted because he saw "evil and corruption everywhere in the Church" and that information was being hidden from the pope.
Many Vatican watchers are sceptical that a butler could have acted totally alone and suggest he may have been forced to take the blame in order to shield bigger players inside the Holy See.
Few people outside the Vatican know what Sciarpelletti looks like. Unlike Gabriele, who rode in the front seat of the popemobile and travelled with the pope, Sciarpelletti worked in an office in one of the Holy See's most secretive departments.
The trial will be covered by a pool of journalists but the court has banned photographers and television from the tribunal.
(Reporting By Philip Pullella; Editing by Robin Pomeroy)