The now 83-year-old Christian brother was jailed in 2011 for more than 14 years after abusing 11 children under his care.

In 2017 he was handed another 10 years and five months over the sexual abuse of another 20 victims between 1969 and 1988 at schools in Ballarat, Box Hill, Geelong and Moonee Ponds.

He pleaded guilty in Warrnambool Magistrates Court to fresh charges of indecent assault of a child under 16 and was sentenced on April 4, 2024, to 18 months' jail.

Magistrate Gerard Lethbridge directed three months be served cumulatively, meaning it won't start until the expiration of Best's prior sentence.

He said the man's offending not only involved sexual crimes against a child but a significant abuse of trust.

"Not only were you a teacher but a religious guide. You had very considerable respect, power and trust," he said.

"Your offending exploited your exalted position and betrayed the trust, not only of your victim but his family and the catholic community."

The magistrate said the offending was also aggravated by Best's manipulation of his victim to remain silent.

A prosecutor previously told the court Best twice sexually assaulted a young boy during counselling sessions at Warrnambool's Emmanuel College in the early 1990s.

He said the offending was a betrayal of trust for both the victim and his parents who had arranged the counselling sessions due to their son going through "normal teenage angst".

"(Best) used his position as a religious leader, a trusted counsellor, to abuse the complainant," he said.

"When later confronted he manipulated the complainant into silence."

The victim said in an impact statement his mental health had deteriorated significantly since the crime and he was left "completely alone" and isolated from his friends and family.

He said he struggled to sleep and suffered night terrors where he was forced to relive the crime in his dreams.

Best has offended against at least 36 separate victims since 1969.

The court heard a County Court judge said in his 2017 sentencing remarks Best had not re-offended since 1988.

The prosecutor said that was now known to be wrong and that Best's "good behaviour" from 1988 onwards had been used as an award in previous sentencing.

"We are dealing with a distinct time period (six years after the matters he was previously dealt with) and not just a separate complainant," he said.

The prosecutor said more jail time was warranted with appropriate accumulation - where sentences are served one after another rather than at the same time.

Lawyer Domenic Care, representing Best, said his client was elderly, vulnerable and "likely to spend the final days of his life in custody".

He said some health issues emerged in 2017, including a cancer diagnosis.

Mr Care said community protection should not form a "meaningful" part of the magistrate's sentencing considerations given Best's age, current earliest release date of March 2028 and the likelihood he "will not see outside of the prison walls".

It is understood Best has not previously been convicted of a crime against a Warrnambool victim.

In sentencing, the magistrate said he considered Best's lengthy time in custody, age, ill health and early guilty plea which prevented the victim from giving evidence in court.

He said accumulation of sentence was called for in recognition of the dignity of the victim, but moderated by principles of totality.