Cardinal George Pell has drawn laughs from observers during the second day of his testimony before the Royal Commission into Institutional Responses Child Sex Abuse, after saying Church leaders were secretive people who always "work with a framework of Christian moral teaching."

As titters rippled around the room, an irritated Cardinal Pell, who began the day saying he had the "full support" of Pope Francis, paused and asked if the Commission would like him to continue.

The cardinal was trying to explain the behaviour of priests – who he described as among the "most secretive of people" – in an effort to convince the Commission that he did not know of the crimes of notorious convicted pedophile Gerard Ridsdale.

Cardinal Pell said he was open to the possibility that several ranking clergymen, including his superior, Bishop Mulkearns, simply lied to him during a 1977 meeting about why Ridsdale was moved from parish to parish, and briefly made an administrator, during that decade.

"I can't remember what reasons were given, but there are many reasons other than pedophilia…to lead to the removal of a priest," Cardinal Pell, who was the episcopal vicar overseeing the education system in the Ballarat region at the time, said.

"I would have had certainly some knowledge (about Ridsdale's circumstances), probably not detailed knowledge," the cardinal said.

"Because obviously there was a series of difficulties (with Ridsdale) but it certainly was not stated that those differences (involved) pedophilia and crime … there would have been some generalised explanation.

"There might have been difficulties with the school principal, differences of personalities, an inappropriate adult relationship, it could have simply been that the man was perpetually restless…"

The Commission then put it to Cardinal Pell that if he didn't know of Ridsdale's crimes – unlike Bishop Mulkearns and several other ranking priests – perhaps he was being intentionally deceived.

"That is correct," Cardinal Pell affirmed.

"There is a saying in the Church," he went on. "Those who know don’t say, and those who say don't know … priests are among the most secretive of people."

It was pointed out to Cardinal Pell that Gerard Ridsdale, who was eventually convicted of 54 child sex crimes, even said himself that his predilections were "common knowledge", but the Vatican's third-most senior figure insisted that he couldn't say whether he "ever knew that everyone knew."

At the beginning of the session, the cardinal drew gasps from the survivors watching his testimony in person in Rome when he said that the crimes of convicted pedophile Gerald Ridsdale were "a sad story and it wasn't of much interest to me".

Cardinal Pell wasgrilled at length about whether he knew of the dozens of sexual crimes committed by Ridsdale against children in Inglewood during the 1970s.

Gail Furness SC had put it to Cardinal Pell that his superior, Bishop Mulkearns, had been informed by a police officer, a Detective Sergeant Mooney, that Ridsdale was under investigation for interfering with children.

The abuse, DS Col Mooney was quoted as saying, was "pretty common knowledge all through the congregation. Pretty much everyone you would speak to knew about it."

"I did not know that it was common knowledge at Inglewood at the time, because if I had known that I would know that there were offences. Possible offences," Cardinal Pell said.

"It's a sad story and it wasn't of much interest to me," he added, to audible shock from onlookers.

"The suffering of course was real and I regret that but I had no reason to turn my mind to the extent of the evils that Ridsdale had perpetrated."

When asked when he knew about Ridsdale's crimes, Cardinal Pell, who was the Bishop of Melbourne when he accompanied Ridsdale to court in 1993, replied: "After he was tried and jailed."