Stephen Douglas Brown, 65, had been working at the Koonawarra Community Centre for little more than a month in late 1986 when he began preying on the teenage boys.

They were lured to his house under the belief they were taking part in a university experiment looking at the correlation between alcohol intake and gross motor skills.

Once Brown had plied them with alcohol - and fed them sleeping tablets - he took advantage of their altered state to fondle and molest them.

He abused four boys in total between November 1986 and August 1988, however only the last two victims reported the assaults to police at the time.

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Brown eventually pleaded guilty to five charges in 1990 and was sentenced to 18 months' weekend detention, placed on a three-year good-behaviour bond and fined $1,000.

His two other victims, brothers then aged 13 and 16, remained silent for more than 30 years, too ashamed to come forward.

But in mid-2017, the oldest brother reported Brown's abuse to police. So had the younger sibling by year's end.

Brown was arrested in January 2018 and charged. He pleaded guilty to three counts of indecent assault and one count of rape ahead of back-to-back trials scheduled for July this year.

In a heart-wrenching statement read out during Brown's sentencing proceedings, the older brother revealed he'd spent most of his life not using the internet out of fear of what he might find.

"Up until 2015 I would not use a computer out of fear I would come across video footage of myself being sexually abused," he said.

"This also impact on my children, who I would not let use computers as I feared that they would come across tapes of their father being sexually abused."

He also said the assaults had left him feeling isolated and alone, telling Wollongong District Court he feared if people found out he was abused by a male, they would think he was gay.

"At the time there were big campaigns regarding homosexuality and the AIDS virus and homosexuality was not accepted as it is now, and should be," he said.

"For anyone to think you were a homosexual put you in a position where you risked being beaten, attacked or raped.

"This resulted in me having to prove that I was not feminine in any way - I got tattoos and did my best to make sure no one would every think I was gay."

The man said he continued to struggle with what had been done to him so long ago.

"So who am I now? I don't think I can even begin to describe in words what you have done to my life....I've been broken for 33 years due to your actions."

The court heard Douglas had been fired from the youth centre in 1988 and had not worked since.

He has been on a disability pension for more than 15 years due to ongoing medical issues associated with his involvement in a high-speed car crash with a drunk-driver in 1977.

When speaking to a psychologist ahead of his sentencing, Brown denied abusing any children in his care, claiming an injury to his elbow made him physically impossible of committing the acts of which he was accused.

When asked why he'd pleaded guilty then, Brown said it was because prosecutors had agreed to reduce the charges against him in exchange for the plea.

In court on Friday, Judge Andrew Haesler noted Brown had a long list of medical conditions that would make time behind bars more onerous for him than a normal prisoner.

Doctors confirmed Brown was currently taking 14 different types of medication.

However, Judge Haesler said Brown had taken advantage of vulnerable victims under the guise of a bogus university study and in doing so, had violated his position of trust.

He sentenced Brown to three-and-a-half years' jail, with a non-parole period of one years and 10 months.

Brown will be released on parole in July 2021.