ROME >> The disclosure this week of a five-page, typewritten document that was stolen from an armored cabinet inside the Vatican has revived the mystery surrounding a 15-year-old who vanished in 1983.

The fate of the teenager, Emanuela Orlandi, has been the subject of much speculation, and the document — purportedly written by a cardinal — suggests that the Vatican may have been directly involved in her disappearance.

The Vatican called the document fake, and a spokesman, Greg Burke, called the allegations contained in it “false and ridiculous.”

Even the investigative journalist who published the document said it could be a fake, noting that it remains unclear who wrote the document, when or — crucially — why.

But the journalist, Emiliano Fittipaldi, who despite his reservations included the typewritten missive in a book to be published this week, says the mere fact that it had been found in a Vatican office raised “very unsettling questions.” The Italian press has reported widely on the case.

Whether genuine, or a forgery intended to “threaten, blackmail or create confusion,” the document “comes from inside the Vatican,” Fittipaldi, one of two reporters tried and acquitted for leaking documents in the so-called “Vatileaks 2” trial, said at a news conference Monday.

“If it is true, it opens up incredible chapters in a story that’s still murky,” he said.

“If it is false, it is equally disturbing,” he added, because it implies behind-the-scenes maneuvers to discredit the Vatican and cause havoc.

He urged the Vatican to disclose whether investigators had ever examined the document — “a poisoned meatball,” he called it — and its provenance.

Orlandi was the daughter of a Vatican employee, making her a citizen of the papal city-state, although she vanished from a Rome street.

Shortly after she disappeared, anonymous calls, presumably by the kidnappers, said the girl would be freed upon the release of Mehmet Ali Agca, the Turkish gunman who tried to kill Pope John Paul II in 1981. (After nearly three decades in Italian and Turkish prisons, Agca was released in 2010.)

Over the decades, other theories emerged, linking the kidnapping to Italy’s secret services or to organized crime. One theory suggested that Orlandi had been abducted at the behest of an American archbishop, Paul C. Marcinkus, a former president of the Vatican bank who was linked to a major scandal and died in 2006.

A gangster’s tomb was exhumed in 2012 for potential clues, but the mystery endured.

The Vatican has said that it has nothing new to say about the case.

The newly disclosed document is titled, “A summary of expenses sustained by Vatican City State for the activities related to citizen Emanuela Orlandi (Rome January 14 1968),” her birthdate.

Supposedly written by one cardinal to two archbishops, it is effectively a running tab of charges incurred between 1983 and 1997 for a total of 483 million lire — which would be about 250,000 euros (nearly $300,000) today.

The itemized costs include various “transfers,” “room and board” in London and elsewhere, and various medical expenses, including for a gynecologist. A number of items refer to Vatican-funded investigations to find her.

Fittipaldi said the document implies that the Vatican succeeded in tracking down Orlandi, but “instead of returning her to her family, they kept her in London, it’s unclear why.” He added that it was “wrong to leap to conclusions.”

The victim’s brother, Pietro Orlandi, who has spent decades searching for the truth of her disappearance, said that if his sister made it to London, it was inconceivable that she would not have reached out.

“It is clear that she wasn’t able to move freely,” Orlandi said in a phone interview. “Should the document be real, it is very serious, because it implicates the Vatican in a kidnapping.”

He called on the Vatican to collaborate in a fresh investigation. “You can’t close a case when new documents emerge after 34 years that still have to be verified,” he said.

The document is believed to be among several others stolen on March 29, 2014, from a locked cabinet in a Vatican office.

A month after the theft, some of the documents — including the one released this week — were returned, with no indication of who had stolen them.

The alleged author of the document, Cardinal Lorenzo Antonetti, died in 2013. The itemized expense account was addressed to two archbishops, now cardinals. One of them, Giovanni Battista Re, told Italian journalists on Monday that he had never laid eyes on it. The other, Jean-Louis Tauran, could not immediately be reached for comment.

Gianluigi Nuzzi, Fittipaldi’s co-defendant in the “Vatileaks 2” trial, plans to publish his own new book about the Vatican in November.

The Orlandi family lawyer, Laura Sgro, said that months ago she had reached out to the Vatican to ask for the Holy See’s documents pertaining to the kidnapping, and to meet with Pietro Parolin, the Vatican’s secretary of state.

“I’ve heard nothing, I haven’t received one piece of paper — zero,” she said.