VATICAN CITY — The biggest scandal to rock the Vatican in decades widened Monday with the pope’s butler, arrested for allegedly having confidential documents in his home, agreeing to cooperate with investigators. That raised the specter that higher-ranking ecclesial heads may soon roll.

Few believe butler Paolo Gabriele worked alone to leak dozens of documents shedding light on power struggles, corruption and intrigue inside the highest levels of the Catholic Church. The leaks have tormented the Vatican for months and painted a picture of a church hierarchy in utter disarray.

Gabriele, the pope’s personal butler since 2006, was arrested Wednesday evening after Holy See documents were found inside his Vatican City apartment, adding an unfathomable Hollywood twist to the already sordid Vatileaks scandal. He remains in custody in a Vatican detention facility, accused of theft, and has met with his wife and lawyers.

Gabriele’s lawyer, Carlo Fusco, said Monday his client was “very serene and calm,” despite the whirlwind of speculation surrounding his arrest. He said Gabriele himself had told the Vatican judge investigating the case that he would “respond to all the questions and will collaborate with investigators to ascertain the truth.”

Italian media reported Monday that a cardinal is suspected of playing a major role in the scandal. However, the Vatican spokesman, the Rev. Federico Lombardi, denied the reports categorically. He said many Vatican officials were being questioned but insisted “there is no cardinal under suspicion.”

But Lombardi acknowledged that the investigation continues.

Also Monday, Italian daily La Repubblica published a rambling interview with what it described as another Vatican “mole,” someone who described the various agendas at play behind the leaks.

The unnamed leaker said the aim was to show how weak Pope Benedict XVI is, the fears of his secretary of state, and to make clear that the “fundamental role of the church is to defend the Gospel, not accumulate power and money.”

Lombardi dismissed as “pure fantasy” such a rash of unsourced reports about the investigation in the Italian media, which have been on a frenzy ever since reports of Gabriele’s detention emerged Friday.

Gabriele, a 46-year-old father of three, was always considered extremely loyal to Benedict and his predecessor, John Paul II, for whom he briefly served. Vatican insiders have said they were baffled by his alleged involvement, and Lombardi said Monday that the entire scandal has caused pain throughout the Vatican.

He acknowledged the “negative image” of the Vatican that was emerging from the scandal.

The Vatileaks scandal broke in January when Italian journalist Gianluigi Nuzzi broadcast letters from the former No. 2 Vatican administrator to the pope in which he begged not to be transferred for having exposed alleged corruption that cost the Holy See millions of euros in higher contract prices. The prelate, Monsignor Carlo Maria Vigano, is now the Vatican’s U.S. ambassador.

The scandal widened over the following months with documents leaked to Italian journalists that laid bare power struggles inside the Vatican over its efforts to show greater financial transparency and comply with international norms to fight money laundering. There was even a leak of a memo claiming that Benedict would die this year.

The scandal reached a peak last weekend, when Nuzzi published an entire book based on a trove of new documentation, including personal correspondence to and from the pope and his private secretary, much of which paints Benedict’s No. 2, Cardinal Tarcisio Bertone, in a negative light.

The Vatican probe into the leaks is actually working on several tracks: Vatican magistrates are pursuing the criminal investigation, and Gabriele was arrested as part of that. The Vatican secretariat of state is pursuing an administrative probe. And the three cardinals appointed by Benedict are acting in a sort of supervisory role, looking beyond the narrow criminal scope of the leaks to interview broadly across the Vatican bureaucracy, Lombardi said.