VATICAN CITY — A painful and damaging chapter in Pope Benedict XVI’s papacy closed Saturday with the conviction of his former butler on charges that he stole the pontiff’s private letters and leaked them to a journalist. But questions remain as to whether anyone else was involved in the plot and on when the pope will pardon his once-trusted aide.

Paolo Gabriele, until recently affectionately dubbed ‘‘Paoletto’’ by his intimate pontifical family, stood stone-faced as Judge Giuseppe Dalla Torre read out the conviction and sentenced him to 18 months in prison for the gravest Vatican security breach in recent memory.

The decision, reached after just two hours of deliberations, capped a remarkable weeklong trial that saw the pope’s closest adviser, Monsignor Georg Gaenswein, and a half dozen Vatican police officers testify about a betrayal of the pope that exposed the unseemly side of the Catholic Church’s governance.

The highest-profile case to come before a court that usually handles 30 cases of petty theft a year ended none too soon: On Sunday, Benedict opens a two-week synod, or meeting of the world’s bishops, summoned to Rome to chart the church’s future evangelization mission and celebrate the 50th anniversary of the Second Vatican Council. By putting the embarrassing leaks scandal behind it, the Vatican has removed a major and unwelcome distraction.

Gabriele was accused of stealing the pope’s private correspondence and passing it on to journalist Gianluigi Nuzzi, whose book revealed the intrigue, petty infighting, and allegations of corruption and homosexual liaisons that plague the Vatican’s secretive universe.

‘The thing I feel strongly in me is the conviction that I acted out of exclusive love.’

Gabriele has said he leaked the documents because he felt that the pope wasn’t being informed of the ‘‘evil and corruption’’ in the Vatican and that exposing the problems publicly would put the church back on the right track.

In his final appeal to the court Saturday morning, Gabriele insisted he never intended to hurt the church or the pope.

‘‘The thing I feel strongly in me is the conviction that I acted out of exclusive love, I would say visceral love, for the church of Christ and its visible head,’’ Gabriele told the court in a steady voice. ‘‘I do not feel like a thief.’’

The sentence was cut in half to 18 months because of a series of mitigating circumstances, including that Gabriele had no previous record, had acknowledged that he had betrayed the pope, and was convinced, ‘‘albeit erroneously,’’ that he was doing the right thing, Dalla Torre said.

Gabriele’s attorney, Cristiana Arru, said the sentence was ‘‘good, balanced’’ and said she was awaiting the judges’ written reasoning before deciding whether to appeal.

Arru said Gabriele would return to his Vatican City apartment to begin serving his sentence. He has been held in house arrest there since July after spending his first two months in a Vatican detention room.

Gabriele was also ordered to pay court costs.

Nuzzi’s book, ‘‘His Holiness: Pope Benedict XVI’s Secret Papers’’ convulsed the Vatican for months and prompted an unprecedented response, with the pope naming a commission of cardinals to investigate the origin of the leaks alongside Vatican magistrates.

Nevertheless, Vatican spokesman Rev. Federico Lombardi said the possibility of a papal pardon was ‘‘concrete, likely’’ and that the pope would now study the court file and decide. He said there was no way to know when a papal pardon might be announced.

In something of a novelty in jurisprudence, the pope was both victim and supreme judge in this case. As an absolute monarch of the tiny Vatican City state, Benedict wields full executive, legislative, and judicial power. He delegates that power, though, and Lombardi said the trial showed the complete independence of the Vatican judiciary.

In her closing arguments, Arru insisted that only photocopies, not original documents, were taken from the Apostolic Palace, disputing testimony from the pope’s secretary who said he saw original letters in the evidence seized from Gabriele’s home.

She admitted Gabriele’s gesture was ‘‘condemnable,’’ but said it was a misappropriation of documents, not theft, and that as a result Gabriele should serve no time for the lesser crime. She also sharply criticized the Vatican for publicly releasing the indictment, since it included elements of Gabriele’s psychiatric evaluation. She said the publication violated her client’s dignity.