Cardinal George Pell says he didn't go to police when a priest who was alleged to have abused 16 children fled to England because there was no concrete evidence against him.

Ronald Pickering, who died in 2009, had his powers as a priest removed in 1994, one year after he fled to England where the Melbourne archdiocese paid him a retirement pension for ten years.

Complaints about him had come from a number of parishes over a 29-year period but he was never charged.

On his fourth day of evidence from Rome, Cardinal Pell also told the commission there was no reason for him to go to police when Pickering fled, but he did tell the then Archbishop Frank Little of rumours about him.

The cardinal was also asked about his knowledge of priest Paul Ryan, who was jailed in 2006 for assaulting an altar boy.

There had been complaints Ryan was abusing children within a week of his ordination in 1973.

Dr Pell said he said he always had reservations about Ryan and was "never supportive" of his priestly vocation because of his "effeminate manner."

When he was sent to the US in 1977 and 1979 by Bishop Ronald Mulkearns, Cardinal Pell said he believed it was for study leave.

"I have mentioned that I regarded him (Ryan) as at least a potential problem. I wasn't aware that there was a pedophilia problem and I thought he was there basically to study," he told the commission.

He added that he could well have imagined the study break was to help him overcome some adult sexual problem.

"But you say that your thoughts were he may have had problems in sexual relations as an adult but not with anyone under the age of 18?" commission chair Peter McClellan asked.

"Not with anyone under the age of 18, yes," Cardinal Pell replied.

It was put to him by counsel representing the mother of Peter Watson, who was abused by Ryan as a child and committed suicide in 1999, that a proper investigation into Ryan earlier would have prevented the death.

"Yes, a proper investigation would have helped impede that," Cardinal Pell replied.

"The responsibility lay with the person who did not act when he should have and that would certainly seem to have been Bishop Mulkearns for sure."