Pope Benedict XVI's onetime butler declared Tuesday he was innocent of a charge of aggravated theft of the pope's private correspondence, but acknowledged he photocopied the papers and said he feels guilty that he betrayed the trust of the pontiff he loves like a father.

Paolo Gabriele took the stand Tuesday in a Vatican courtroom to defend himself against accusations of his role in one of the most damaging scandals of Benedict's pontificate. Prosecutors say Gabriele stole papal letters and documents alleging power struggles and corruption inside the Vatican and leaked them to a journalist in an unprecedented papal security breach.

Gabriele faces four years in prison if he is found guilty, although most Vatican watchers expect he will receive a papal pardon if he is convicted.

Prosecutors have said Gabriele, 46, has confessed to leaking copies of the documents to Italian journalist Gianluigi Nuzzi, because he wanted to expose the "evil and corruption" in the church. They quoted him as saying in a June 5 interrogation that even though he knew taking the documents was wrong, he felt inspired by the Holy Spirit "to bring the church back on the right track."

Judge Giuseppe Dalla Torre asked Gabriele on Tuesday if he stood by his confession. Gabriele responded: "Yes."

Asked, though, by his attorney Cristiana Arru how he responded to the charge of aggravated theft, Gabriele said: "I declare myself innocent concerning the charge of aggravated theft. I feel guilty of having betrayed the trust of the Holy Father, whom I love as a son would."

He insisted he had no accomplices, though he acknowledged that many people inside the Vatican, including cardinals, trusted him and would come to him with their problems and concerns. He said he felt inspired by his faith to always give them a listen.

He acknowledged he photocopied papal documentation, but insisted he did so in plain view of others and during daylight office hours, using the photocopier in the office he shared with the pope's two private secretaries.

The trial opened over the weekend inside the intimate ground-floor tribunal in the Vatican's courthouse tucked behind St. Peter's Basilica. Dalla Torre has said he expects it to be over within three more hearings.

In addition to Gabriele, the court heard Tuesday from four witnesses, including the pope's main private secretary, Monsignor Georg Gaenswein, who along with Gabriele was the closest assistant to the pontiff.

Gaenswein testified that he began having suspicions about Gabriele after he realized three documents that appeared in Nuzzi's book could only have come from the office he shared with Gabriele and Benedict's other private secretary.

"This was the moment when I started to have my doubts," Gaenswein said.

The book, "His Holiness: Pope Benedict XVI's private papers," became an immediate blockbuster when it was published May 20, detailing intrigue and scandals inside the Apostolic Palace. The leaked documents seemed primarily aimed at discrediting Benedict's No. 2, Cardinal Tarcisio Bertone, often criticized for perceived shortcomings in running the Vatican administration.

Gaenswein said as soon as he read the book, he immediately asked the pope's permission to convene a meeting of the small papal family to ask each member if he or she had taken the documentation.

One member, Cristina Cernetti, one of the pope's four housekeepers, told the court she knew immediately that Gabriele was to blame because she could exclude without a doubt any other member of the family.

In an indication of the respect Gabriele still feels for Gaenswein, he stood up from his bench when Gaenswein entered the courtroom and then again when he exited. Gaenswein didn't acknowledge him.

The trial resumes Wednesday with the testimony of four members of the Vatican police force who conducted the search of Gabriele's Vatican City apartment on May 23. In testimony Tuesday, two police officers said they discovered thousands of papers in Gabriele's studio, some of them originals.

During the testimony, the lawyer Arru complained about the conditions under which Gabriele spent his first 20 days in detention, saying the cell was so small he couldn't stretch out his arms and that lights were kept on 24 hours a day.

Gabriele said those conditions contributed to his "psychological depression."

Dalla Torre invited the prosecutor to launch an investigation, which he did. Vatican spokesman the Rev. Federico Lombardi said the size of the cell conformed to international standards and that, anyway, Gabriele was moved to a bigger cell.

The Vatican police responded quickly with a lengthy statement insisting that Gabriele's rights had been respected, citing the food, free time, socializing, spiritual assistance and health care that Gabriele enjoyed during his nearly two months of detention. They said the lights were kept on for security reasons and to ensure Gabriele didn't harm himself, and that he had a mask he could use to block out the light.

The police warned that they may file a counter complaint against Arru if the investigation shows no wrongdoing on their part.

The trial is being conducted according to the Vatican's criminal code, which is adapted from the 19th-century Italian code. The court reporter doesn't take down verbatim quotes, but rather records reconstructed summaries dictated to her by the court president, Dalla Torre.

On several occasions, Dalla Torre truncated the responses or, with the help of the notary and the prosecutor, reconstrued them, occasionally attributing to Gabriele and other witnesses words they didn't necessarily utter, or leaving out parts of their testimony altogether. For example, the recorded summary of Gabriele's plea didn't include that he loved the pope as a son would.

The recorded testimony was read aloud to each witness for any corrections at the end. Gabriele was able to make corrections as each summary was recorded, but his full testimony was not read back to him at the end.

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