Pope Francis has moved Pope John Paul I, the pope who reigned for only 33 days in 1978, a step closer to possible sainthood just days after the Vatican endorsed

The Vatican said on Thursday that Francis signed a decree declaring that John Paul I had lived a life of heroic virtue.

The Vatican must confirm a miracle attributed to his intercession for the late pope to be beatified, and a second miracle for him to be made a saint.

Earlier in the week, a book titled Pope Luciani: Chronicle Of A Death went on sale in Italy.

It stated that John Paul I, the former Cardinal Albino Luciani, died of a heart attack at the age of 65.

Pope Francis exchange gifts with Paraguay president Horacio Cartes during a private audience at the Vatican Thursday, Nov. 9, 2017.

The author, journalist Stefania Falasca, was involved in the beatification cause and had access to confidential Vatican documents, including John Paul's medical file.

The book features a preface by the Vatican secretary of state, Cardinal Pietro Parolin, who said it was time to move on and appreciate John Paul I's legacy and historic value to the Catholic Church.

Conspiracy theories have swirled for decades that Luciani was murdered in the Apostolic Palace as part of a plot involving the Vatican's scandal-marred bank.

His September 28 1978 death led to the election a few weeks later of the Polish cardinal, Karol Wojtyla, who took inspiration from his predecessor and named himself Pope John Paul II.