The then Father Wilson had information indicating McAlinden had sexually abused children from 1986, Commissioner Margaret Cunneen said in the fourth volume of her report following a Special Commission of Inquiry in 2013, which was withheld until today after the archbishop was charged with concealing the crimes of another Hunter priest, Jim Fletcher.

Archbishop Wilson was convicted in May, 2018 but was acquitted after the matter was overturned on appeal in December, 2018.

Ms Cunneen found the then Father Wilson received a direct report from a close friend of his, a woman known as AJ, in the 1980s alleging sexual abuse by McAlinden years earlier, and in 1987 he investigated complaints about McAlinden's conduct with young girls in Merriwa, including obtaining a statement from a victim's mother.

"During the same year Wilson had a central role in communicating with high-profile MP John Hatton in relation to the diocese's management of the McAlinden problem, in addition to making arrangements for McAlinden's psychiatric evaluation," Ms Cunneen found.

"In 1995 Wilson obtained further information - including statements from two further victims, AK and AL - about McAlinden's propensity to sexually abuse children.

"Thus, from 1986 onwards Wilson possessed information that would have facilitated and/or assisted a police investigation of McAlinden. Further, by at least 1995, if not earlier, Wilson should have been, and was, aware that Bishop Leo Clarke had no intention of reporting McAlinden to police.

"Wilson should have reported McAlinden to police - including by using the option of blind-reporting from 1997 onwards. His failure to do so constitutes a failure to facilitate and/or assist a police investigation of McAlinden."

In May last year Archbishop Wilson was the most senior Catholic clergyman in the world to be convicted of concealing the child sex crimes of a priest after he was charged in March, 2015 with failing to report allegations about Hunter priest Jim Fletcher to authorities.

The conviction was overturned in December when Newcastle District Court Judge Roy Ellis found the archbishop, 68, was an "honest, intelligent and articulate witness" who did not attempt to blacken the name of Hunter man Peter Creigh, who alleged he told the archbishop about Fletcher in 1976.

The Commission of Inquiry confidential report found Hunter survivor advocate Peter Gogarty was sexually abused by Jim Fletcher in the 1970s, but it was not open to the Commission to conclude that the then Father Wilson knew or should have known Fletcher was sexually abusing Mr Gogarty, then 13 or 14, at Maitland's Bishops House where both priests lived.

The Commission was satisfied that a report to Father Wilson in 1976 alleging sexual abuse of a young boy by Fletcher, "would have put Wilson on notice about Fletcher's propensity to sexually abuse young boys".

"Wilson would have had good reason to be particularly alert to the implications of teenage boys (such as Gogarty) attending the bishop's house while Fletcher was in residence," the Commission found.

It found former Maitland-Newcastle Bishop Michael Malone "deliberately failed" to mention the existence of a victim of Jim Fletcher when interviewed by Strikeforce Lantle police in November, 2011 and questioned about his knowledge of Fletcher's victims.

The then Hunter Bishop failed to disclose contact from 2010 with a man who alleged he told the then Father Philip Wilson about sexual abuse by priest Jim Fletcher in 1976, an allegation that "potentially constituted a criminal offence", the Commission found.

Bishop Malone failed to disclose the man and his allegation to Strikeforce Lantle Detective Jeff Little in November, 2011 despite meeting with the man, later identified as Peter Creigh, by himself at Mr Creigh's home in 2010.

Detective Lantle was investigating how the diocese responded to child sex allegations involving priests, including an attempted secret defrocking of notorious Hunter paedophile priest Denis McAlinden in 1995 where Bishop Malone and Father Wilson had formal roles.

In the confidential fourth volume of the NSW Special Commission of Inquiry into how NSW Police and the Catholic Church responded to child sex allegations, released today more than five years after the first three volumes were released in 2014, Commissioner Margaret Cunneen criticised Bishop Malone for "a failure to facilitate the Strikeforce Lantle investigation".

His failure to disclose Mr Creigh as a fourth known victim of Fletcher made it less likely matters relating to the archbishop would come to police notice, unless Mr Creigh took further action.

"Such reporting was a step Malone should have taken, in particular as head of the diocese," the Commission found.

It rejected the bishop's statement he "simply forgot to mention" the existence of a fourth Fletcher victim when directly questioned by Detective Little about his knowledge of other Fletcher victims.

The Commission found Bishop Malone formed the view Mr Creigh was "a credible and impressive man".

The bishop's failure to mention Mr Creigh during the interview "was deliberate", the Commission found.

While he offered "a form of assistance" to the Strikeforce Lantle investigation by voluntarily attending to answer questions on November 30, 2011, and making a statement in September, 2013, "there was a deliberate withholding from the Lantle investigators of information that Malone would have known was relevant".

The allegation of a potential cover-up, as put to Bishop Malone by Mr Creigh, "would obviously have been of great assistance to the Strikeforce Lantle investigators", the Commission said.

"The answer Malone gave when questioned about his knowledge of victims of Fletcher misled Detective Sergeant Little into believing that Malone knew of no other victims. This was not the true position, and Malone did not ever correct it through subsequent contact with Little."

Mr Creigh made direct contact with Detective Little during the Special Commission of Inquiry in 2013.

The Commission found no evidence the bishop sought to dissuade Mr Creigh from reporting his complaint to authorities, and did not destroy documents.

The bishop also had an "open house" policy on access to diocese records in his office, the Commission found.

But it found "significant institutional failings" in its child protection unit, Zimmerman Services', handling of Mr Creigh's complaint in 2010 and 2011, including the actions of service manager Sean Tynan after he became aware of the complaint.

Mr Tynan failed to ask Bishop Malone for a copy of the original complaint, failed to read a clergy review analysis document to "inform himself about Wilson's concealing of child sexual abuse matters", failed to provide a support staff member with information about the complaint or to follow up with Bishop Malone about the complaint's status.

Two other Zimmerman Services investigators were also aware of the material "but took no substantive steps to ensure that police became aware of the information", the Commission found.

While the actions of Mr Tynan and the two investigations was not calculated to conceal the information about Archbishop Wilson, "the totality of the evidence points to an institutional failure by Zimmerman Services to discharge its responsibilities", the Commission found.

"These systemic flaws are such that, as a child protection institution, Zimmerman Services failed to assist or facilitate relevant police investigations, in that it failed to report to police potential criminal offences."

The service revised its reporting policies because of the "deficiencies uncovered" during the Commission's investigations, the report found.

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