A 13-year-old boy was told he was "pleasing a man of God" as his music teacher forcefully sexually abused him after band practice, a jury has heard.
Catholic priest and former high school teacher Anthony William Peter Caruana, 79, is also accused of sexually abusing boys at rugby training, a swimming carnival, a bus and in the dorm rooms of Chevalier College, south of Sydney, in the 1980s.
He has pleaded not guilty in the Sydney District Court to 29 historical charges, including four counts of homosexual sex.
One former student, now in his 50s, is expected to tell the jury he was in a band storage room cleaning instruments in 1984 when Caruana grabbed his hand and forced it down the teacher's pants.
Caruana said words to the effect of "God will love you if you do what I say" and "you're pleasing a man of God" as the boy struggled against his grip, crown prosecutor Nerissa Keay expects the complainant will tell the trial.
Another 11 students are due to give evidence of being indecently assaulted by Caruana.
One is due to say Caruana grabbed and held onto his genitals while showing 12-year-olds how to pack a scrum at rugby union training.
"I expect (the former student) will say he thought that was how scrums occurred because that happened to him on a number of occasions," Ms Keay said.
Caruana left the school in the NSW Southern Highlands in 1989 after complaints were made about his conduct towards boys.
That same year, a questionnaire was filled out in Caruana's handwriting that the Crown says "demonstrates" the priest's contemporaneous sexual interest in boys aged 11 to 15.
One response spoke of feeling there might be something wrong with "my sexual problem".
"I was always worried it would be found out and now that it has, it has shattered me," read an answer to a question about having a "bad feeling".
When asked about any desire to change something by "magic", the respondent said: "This feeling I have towards young boys".
The Crown is also expected to call one of Caruana's former managers in the Missionaries of the Sacred Heart.
That priest wrote a file note in 1993 that "Tony acknowledges he is a pedophile and there is little likelihood of change," Ms Keay said.
She added the priest couldn't specifically recall writing the note but he will tell the jury "he wouldn't have written it if that wasn't said to him".
Caruana's lawyer urged the jury not to decide anything until they'd heard the entirety of the evidence.
"We all know the sound that liars make when they give untruthful stories and sometimes intelligent questioning reveals more," barrister Bernard Brassil said.
"Please be patient."
The trial is expected to run for more than a month.