Prosecutor David Cordy, in his closing address in the trial of former Salesian priest David Edwin Rapson, told the County Court he wanted to "debunk" some of the theories put forward by the accused man's barrister during the trial.

Mr Cordy said it was the inference of defence counsel Shaun Ginsbourg that the complainants could not be reliable in their evidence because were teenage boys at the time of the alleged offences, nor could some of them be trusted because of their own legal problems as adults.

Mr Rapson, 60, has pleaded not guilty to eight charges of indecent assault and five counts of rape related to alleged incidents involving eight boys between the mid 1970s and 1990.

One of the complainants alleges he was raped on four separate occasions in 1990.

Mr Cordy told the jury on Monday that Mr Ginsbourg had inferred the complainants told "a pack of lies" by asking them if it could have been someone else who abused them.

"It is a fanciful argument to say that a 13 or 14 or 15 or 16-year-old boy wouldn't know who touched him in a school environment when the person who touched him is known to him ... That is just a furphy," he said.

"Did any one of them present to you as a liar?"

Mr Cordy acknowledged some of the complainants had gone through legal problems of their own, including armed robbery offences and in one case, one being jailed for the sexual penetration of a 16 or 17-year-old, and that some had considered suing Mr Rapson for compensation.

But he said all the complainants were emphatic they were sexually abused by the accused man and indignant when it was suggested to them that they were not telling the truth.

He urged the jurors to put themselves in the position the complainants faced when abused at a Catholic boarding school in "less enlightened times" and were embarrassed, shamed and "powerlessness" to challenge those in authority.

"You have got people in authority, such as brothers and priests, and Mr Rapson was both, and you can imagine the relative power, the complainant on one hand and the father on the other ... if anyone said anything it was just swept under the carpet," he said.

"That's the way it was back then."

Mr Ginsbourg had only 10 minutes to address the jury before court was adjourned on Monday afternoon, but stressed the importance of listening to what the witnesses said in their evidence, rather than watch for how they said it.

Mr Ginsbourg will resume his closing address on Tuesday.

The jury will begin deliberations either on Tuesday afternoon or Wednesday, after instruction from Judge Liz Gaynor.