Pope Francis to beatify 'Smiling' John Paul I

Pope Francis will preside Sunday over the beatification of John Paul I, the so-called "Smiling Pope" who led the Catholic Church for just 33 days before dying in contested circumstances.

Thousands of people are expected to attend the mass in St Peter's Square where the former pontiff will become "blessed" -- the final step before becoming a saint.

John Paul I, the son of a bricklayer from the Dolomite mountains and a particularly warm and pastoral figure, was elected pope on August 26, 1978, at the age of 65.

He died just 33 days later, on September 28, 1978, of a heart attack, making him the shortest serving pontiff in modern church history.

His death sparked intense speculation as to the cause, from suicide -- he seemed reluctant to take on the position of pope -- to murder, allegedly by those who opposed his plans to reform the church, particularly the powerful Vatican bank.

Many have since discounted this and biographer Christophe Henning said the swirling rumours can be explained by the sudden nature of his death and the "calamitous communication" by the Vatican at the time.

No autopsy was conducted to determine the cause of death, and the Vatican issued inconsistent and...