Australian Cardinal George Pell will come under international scrutiny when he testifies, from Rome, before the Royal Commission into child sex abuse.
Catholic sex abuse victims and their supporters are now also in Rome for his appearance.
This is Cardinal Pell's third time at the child abuse royal commission.
The focus this time is on the Catholic Church's handling of child sex abuse allegations in Victoria's Diocese of Ballarat and the Archdiocese of Melbourne.
Cardinal Pell was a Ballarat priest (1973-1984) and as the diocese's episcopal vicar for education oversaw schools including St Alipius where four Christian Brothers were pedophiles.
He was one of Ballarat Bishop Ronald Mulkearns' advisers, at a time when there were pedophile priests in the diocese and was at meetings where the appointment of priests was discussed.
Cardinal Pell and another priest lived in a presbytery with pedophile priest Gerald Francis Ridsdale in 1973.
As a Melbourne auxiliary bishop (1987-1996) he was responsible for areas where at least one offending priest was located, and was a member of the archbishop's personnel advisory board and the curia.
He then became Melbourne archbishop (1996-2001).
Why he is in Rome and not Sydney
Cardinal Pell was to give evidence in person before medical advice that he should not take a long-haul flight due to a worsened heart condition.
The commission in the end agreed he could give videolink evidence from Rome to a hearing in Sydney.
It then agreed survivors could be in the Rome hotel conference room with Cardinal Pell when he gives his evidence.
Second Commission appearance, August 2014
Cardinal Pell gave videolink evidence from the Vatican to a Melbourne hearing focused on the Melbourne Response, the abuse complaints handling scheme he set up in 1996.
Cardinal Pell said they never anticipated the volume of responses and that the scheme would go on for years.
He attracted outrage by saying the Catholic Church is no more legally responsible for priests who abuse children than a trucking company which employs a driver who molests women.
The commission found the Melbourne Response is not independent, is overly legalistic and should leave it to the police to advise abuse victims about potential charges.
First Commission appearance, Sydney, March 2014
Cardinal Pell gave evidence in person to a hearing about abuse victim John Ellis' legal case, from his time as Sydney archbishop (2001-2014).
Mr Ellis failed in his attempt to sue the Archdiocese of Sydney's trust when a court ruled it could not be held liable, a ruling setting the Ellis defence precedent that has been a roadblock to litigation for other abuse victims.
Cardinal Pell admitted the Catholic Church did not deal fairly with Mr Ellis "from a Christian point of view", but in a legal sense it did nothing improper.
In an apology, he said the church had failed Mr Ellis and as archbishop he took ultimate responsibility for the suffering and the terrible impact on his life.
The commission found the archdiocese was wrong in concluding the priest did not abuse Mr Ellis and that Cardinal Pell accepted legal advice to vigorously defend the claim so as to deter other victims from suing the church.
