Cardinal George Pell will learn whether his appeal against child sex abuse convictions has been successful Tuesday, when Australia's High Court hands down its judgement. The former Vatican treasurer is trying to overturn a six-year sentence for sexually abusing two 13-year-old choirboys at a Melbourne cathedral in the 1990s. Pell, who once helped elect popes, is the highest-ranking Catholic Church official ever convicted of child sex crimes. He maintains his innocence. The 78-year-old was found guilty on five charges by a jury in December 2018 before losing his first appeal in Victoria state's Court of Appeal last August. Judges could yet deny Pell's appeal, order a retrial or quash his conviction altogether. One of Australia's highest-profile court cases, the judgement will be delivered to a near-empty Brisbane courtroom as coronavirus social distancing measures limit the public gallery to a maximum of three people. That is in stark contrast to earlier hearings which have drawn large crowds of his supporters and detractors, the world's media, and members of the legal profession. The case relied largely on the testimony of Pell's surviving victim, who testified in a closed-door hearing. The second choirboy -- who is not known to have ever spoken of the abuse -- died of a drug overdose in 2014. Neither man can be identified for legal reasons. Pell was quietly removed from top Church bodies while a wide-ranging court gag order suppressed mention of his trial, but he remains in the priesthood. The Vatican previously said it would avoid launching an investigation into his conduct until after all legal avenues are exhausted.