A former Catholic priest who showed pornographic images to children and assaulted a teenager while he slept has been jailed for two years and two months for historic sexual assault offences.

Key points: The sexual assaults happened while Ryan was an assistant priest in Warrnambool and Ararat

The sexual assaults happened while Ryan was an assistant priest in Warrnambool and Ararat Through a victim impact statement the court heard one man describe how visions of the offending were "burned inside" him

Through a victim impact statement the court heard one man describe how visions of the offending were "burned inside" him Ryan will be eligible for parole next year

Paul David Ryan, now a 70-year-old pensioner, was charged after a 2016 police investigation sparked by the sex abuse royal commission.

The charges relate to three boys, who were aged 14, 15 and 17 at the time of the assaults.

The first boy was training to be an altar boy and the other two were students at the Warrnambool Christian Brothers' College, where Ryan worked as a school chaplain and provided sex education classes.

Victorian County Court Judge Susan Pullen described the crimes as "brazen", "humiliating and degrading", and said they occurred against a backdrop of careful grooming.

During his sentencing today, Judge Pullen told the court the former priest used the power he wielded "to facilitate" his crimes and that this power made his victims especially vulnerable.

The court heard Ryan asked one victim questions about masturbation during confession, bought the students alcohol and cigarettes, and showed them pornographic magazines that he carried around in a briefcase featuring naked men.

The offences occurred mainly in a religious setting.

Sent to US for 'treatment'

Ryan assaulted the 15-year-old boy in 1981 in the sacristy of St Joseph's church in Warrnambool where he worked as an assistant priest.

The court heard he grabbed at the boy's genitals after checking to see how well the altar boy's robes fitted and while the boy's mother waited for him in the car outside.

The 17-year-old student was confronted by Ryan in 1985 during a religious retreat for students at Lower Plenty.

The boy woke up to find the priest with his head over the student's groin.

Ryan, who was aged 37 at the time, then proceeded to masturbate and orally rape the boy.

In 1992, Mr Ryan was appointed assistant priest at Ararat, where he found his third victim — a 14-year-old altar boy.

The priest would hold regular get-togethers with about six altar boys on Saturday nights at the presbytery.

One night, when the 14-year-old and Ryan were playing cards alone, Ryan changed the game to strip poker.

When the boy was dressed only in his underwear the priest knelt down in front of him and rubbed his penis.

In sentencing Ryan, Judge Pullen noted the former priest had been sent to receive "treatment" in the United States after his ordination in 1976.

Catholic authorities were concerned about Ryan's sexual activity with other seminarians when he was training to be a priest in Melbourne, and the royal commission heard evidence that a mother had approached Ballarat's former bishop, Ronald Mulkearns, with claims the priest had assaulted her son almost immediately after his ordination.

The court heard that he was placed "on notice" from Catholic authorities not to reoffend in 1980.

"The speed at which you reoffended is alarming," Judge Pullen said.

It wasn't until 1993 that he was defrocked.

Judge Pullen told the court the sexual assaults happened against a backdrop of grooming.

"Weapons were not needed to gain compliance," she said.

"I do not accept you have accepted full responsibility of your offending."

A psychologist's report submitted to the court identified a range of cognitive distortions that underpinned Ryan's offending.

It noted he held the view that the teenagers were able to make informed choice about whether or not they wanted to participate in the sexual activity.

"These misconceived beliefs provided a context in which Mr Ryan felt able to abdicate his adult responsibilities and prioritise his own pleasure," the report said.

'Joy of companionship' taken

One of the three victims attended court for Ryan's sentencing flanked by supporters.

The judge relayed the lifelong impact that the offences had on his ability to form relationships.

In his victim impact statement the now 51-year-old victim said he had never allowed anybody to get close to him as a result of Ryan's actions and said had been robbed of "the joy of companionship".

He said his trust had been breached and that he suffered from post-traumatic stress and had a fear of enclosed spaces.

Judge Pullen noted the victim had approached the former Bishop of Ballarat, Ronald Mulkearns in the 1990s to report the abuse and was specifically told not to go to the police.

The man said he felt guilty about the inaction, and believed there was "no cure" or healing possible for him.

Reading from the victim impact statement of Ryan's Ararat victim, now aged 42, Judge Pullen told the court the offences had changed the man's life forever and left him with visions which continued to haunt him.

Those visions "burned inside" him for years without anyone knowing, Judge Pullen read.

Ryan was sentenced to a minimum of 17 months' jail, which amounts to 13 months' after time served.