CANBERRA (Reuters) - Lawyers for George Pell began a final bid on Wednesday to overturn the former Vatican treasurer’s conviction for sexually abusing two choirboys, arguing in Australia’s highest court that he could not have committed the offences.

FILE PHOTO - Vatican Treasurer Cardinal George Pell is surrounded by Australian police as he leaves the Melbourne Magistrates Court in Australia, October 6, 2017. REUTERS/Mark Dadswell/File Picture

Cardinal Pell, 78, began serving a six-year prison sentence a year ago, becoming the highest ranking Catholic clergyman worldwide to be jailed for child sex offences.

The High Court of Australia began a two-day hearing on Wednesday that marks Pell’s last avenue of appeal. The seven justices could throw out his application. If they proceed, they have the options of acquitting Pell, rejecting his appeal or sending the case back to a lower court.

Pell was convicted by a jury in December 2018 and sentenced in March 2019 on one charge of sexual penetration of a child under 16 and four charges of an indecent act with a child under 16. The offences occurred in the 1990s when Pell was archbishop of Melbourne.

Pell went to the High Court after losing a previous appeal to the lower Court of Appeal in the state of Victoria where a 2-1 majority upheld his conviction, finding that it was open to the trial jury to find Pell guilty beyond reasonable doubt.

Pell’s legal team outlined the core of their argument in the High Court on Wednesday. They contend that the Victorian Court of Appeal majority verdict erred by shifting the onus of proof to the defense, and incorrectly concluded it was open to the trial jury to be satisfied beyond reasonable doubt that Pell was guilty.

Pell’s lawyer highlighted testimony from the trial that he said would have made it impossible for Pell to have been alone in the priests’ sacristy of St Patrick’s Cathedral in Melbourne in his robes with two boys shortly after mass, where four of the offences occurred.

“The evidence was all one way concerning what was an important aspect of protocol – the applicant would never be left alone while robed,” Pell’s lawyer, Bret Walker, told the court.

Walker said Pell was always on the front steps of the church after mass for at least 10 minutes, which would have made it impossible for him to have been in the priests’ sacristy in the timeframe shortly after mass when the offences occurred.

“The crown case simply could not eliminate the grounds of reasonable doubt, because there was simply not the available time for it to occur,” he told the court.

If the court decides against throwing out the appeal and hears the full case, a judgment would likely be handed down in several months.

VIDEO EVIDENCE

Judges questioned Walker about whether the Court of Appeal had erred in watching videos from the trial, rather than relying only on transcripts.

Walker said videos could have led the judges to focus too much on the credibility of the complainant and other witnesses rather than issues that could have raised doubt for the jury.

“It gives rise to a real danger that the appellate court would enter into an out and out credibility assessment for itself, whereas the real question is ... was the jury in a position where it was open to find guilt beyond a reasonable doubt,” he said.

Judges also asked Walker whether it was right for the appeal court judges to have tried on the archbishop’s robes to see if they could be parted as described by his victim at the trial.

Walker said he had no issue with that experimentation and conceded that the judges may have wanted to see whether loosening the cincture, or rope belt, around the robe would allow the vestments to be moved.

The hearing continues on Thursday, when the Crown will argue its side.