VATICAN CITY -- A painful and damaging chapter in Pope Benedict XVI's papacy closed Saturday with the conviction of his former butler on charges 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 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: Today, 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.

Gabriele has said he leaked the documents because he felt 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 reduced in half to 18 months from three years 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 the 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 reading the sentence, however, in a courtroom decorated with a photograph of Benedict on the wall opposite the man who betrayed him, Dalla Torre began: "In the name of His Holiness Benedict XVI, gloriously reigning, the tribunal invoking the Holy Trinity pronounces the following sentence ..."

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.

With the trial over, several questions still remain about the leaks, most importantly whether Gabriele acted alone.

In his testimony this week, Gabriele insisted "in the most absolute way" that he had no accomplices.

But in earlier statements to prosecutors, he named a half dozen people including cardinals and monsignors with whom he spoke and said he received "suggestions" from the general environment in which he lived. He even identified one layman as the source of a segment of Nuzzi's book detailing some conflicts of interest of some Vatican police officers.

But in his closing arguments, prosecutor Nicola Picardi said the investigation turned up no proof of any complicity in Gabriele's plot. "Suggestions aren't proof of the presence of accomplices," he said.

However, Nuzzi wasn't the only one to publish leaked Vatican material this year. Italian newspapers were filled with leaked Vatican memos earlier in the year, many of them concerning the Vatican's efforts to comply with international financial transparency norms. None of those leaks were mentioned in the trial, and based on the contents, they came from sources other than the papal apartment.

There is another suspect in the case: Claudio Sciarpelletti, a 48-year-old computer expert in the Vatican secretariat of state who is charged with aiding and abetting the crime. Police say they found an envelope in his desk that said "Personal P. Gabriele" on it, with documentation inside.

Sciarpelletti has said Gabriele gave him the envelope, and later, that someone identified in court documents as "W" gave it to him to pass onto Gabriele.

Sciarpelletti's lawyer successfully got his case separated out at the start of Gabriele's trial. But attorney Gianluca Benedetti has said his client was innocent and that, regardless, there were no "reserved documents" in the envelope.