Former aide to pope serving a six-year sentence for sexually abusing two choirboys appears in Victoria Supreme Court.

Disgraced Cardinal George Pell, the Vatican’s former number three, has appeared in an Australian court for an appeal hearing against his convictions for child sexual abuse.

The 77-year-old was convicted in December on five counts of assaulting two choirboys in a Melbourne cathedral in 1996 and 1997. He was sentenced in March to six years in prison.

Pell’s lawyers say his conviction was unreasonably based on the testimony of a single surviving victim and that the judge unfairly disallowed defence evidence.

The second victim died of a drug overdose in 2014 and never disclosed the abuse.

Pell on Wednesday wore his clerical collar and a black coat for the appeal, which was being heard by three judges of Victoria State’s Supreme Court. He was not required to go to court.

The hearing is scheduled to continue on Thursday before the three judges make a decision on his case, a process that could take several weeks.

They could reject the appeal, order a retrial or acquit Pell. Any ruling could be appealed further to Australia‘s High Court.

Prior to Wednesday’s hearing, the three judges visited Melbourne Saint Patrick’s Cathedral to understand the evidence that was being considered by the jury, a court spokesperson said.

Pell, a former Vatican treasurer and adviser to Pope Francis, is the highest-ranking Roman Catholic Church cleric worldwide to be convicted of child sex offences.

The cleric has always maintained his innocence and the defence argues that the timing of the assaults was “impossible” given the dates and his publicly verified movements within the cathedral.

The appeal also says it was not possible for the two choirboys to have left their group unnoticed or for the sexual assault in the sacristy to have gone undetected when the cathedral was busy following mass.

The victim’s testimony and cross-examination were given to the jurors and judge alone. A video of that cross-examination is expected to be reviewed by the appeal judges.