Cardinal George Pell, the most senior Catholic found guilty of child sex abuse, will be released from prison after his convictions were quashed.

The Australian High Court dismissed the convictions of Pell, with chief justice Susan Kiefel announcing the decision of the seven judges was unanimous.

The decision means he will be released from Barwon Prison near Melbourne.

Pope Francis’ former finance minister was convicted in 2018 of sexually abusing two 13-year-old choirboys in a back room of St Patrick’s Cathedral in Melbourne in December 1996 while he was archbishop of Australia’s second-largest city.

Pell was also convicted of indecently assaulting one of the boys after a Mass in early 1997.

The 78-year-old cleric has served more than a year of a six-year sentence.

The High Court found that the Victorian Court of Appeal was incorrect in its 2-1 majority decision in August to uphold the jury verdicts.

Pell was regarded as the Vatican’s third-highest ranking official when he voluntarily returned to Melbourne in July 2017 determined to clear his name of dozens of decades-old child abuse allegations.

All the charges were dropped by prosecutors or dismissed by courts in preliminary hearings over the years except those relating to allegations at St Patrick’s.

Pell, reading from a prepared statement at a police interview in 2016, said: “The allegations involve vile and disgusting conduct contrary to everything I hold dear and contrary to the explicit teachings of the church which I have spent my life representing.”

He also pointed out that had had established a world-first compensation scheme for victims of clergy, the Melbourne Response, months before the crimes were alleged to have occurred.

As police detailed the abuse allegations, Pell responded: “Absolutely disgraceful rubbish. It’s completely false. Madness.”

Much of the two-day High Court hearing focused on whether the jury should have had a reasonable doubt about Pell’s guilt and whether he could have time to molest the boys in five or six minutes immediately after a Mass.

During the hearing, Pell’s lawyer Bret Walkers said all that the prosecution had to do at his trial and appeals court hearing was to prove that Pell being left alone while robed or not talking with congregants after Mass was “possible” to prove guilt beyond reasonable doubt.

“That… is a grotesque version of the reversal of onus of proof, if all the Crown has to do is to prove the possibility of something,” he said.