But Mr Barbour admitted to a parliamentary inquiry on Friday that Deputy Police Commissioner Nick Kaldas was not one of those asked to "show cause" in relation to potential findings.

This was despite Mr Barbour having sought advice from the Director of Public Prosecutions last November about possibly bringing charges against Mr Kaldas over allegedly misleading his inquiry.

Asked by Greens MP David Shoebridge why Mr Kaldas was not afforded the "procedural fairness" others facing adverse findings enjoyed, Mr Barbour said the matter was subject to legal professional privilege and could not answer.

Mr Barbour also told the parliamentary inquiry he is satisfied a leak of information damaging to Mr Kaldas in relation to the scandal did not come from his office.

A Fairfax Media article in April revealed Mr Barbour was considering seeking advice from the Director of Public Prosecutions about potential criminal charges against Mr Kaldas for allegedly misleading his inquiry.

In a sensational development on Thursday night it emerged a senior NSW Crime Commission investigator Tim O'Connor told the inquiry he suspected the leak had emanated from the Ombudsman's office.

This was based on a conversation he said he had with the article's author, journalist Nick McKenzie, who he said told him he discussed the matter with three investigators in the Ombudsman's office. However, McKenzie has said the source of the information was not from within the Ombudsman's office.

On Friday Mr Barbour said his staff had told him that they did not leak the information and the three investigators signed statutory declarations that they had not spoken to McKenzie or other journalists. He said he was "completely satisfied" there had been no leak from his office.

The article outlined the allegation Mr Kaldas misled Mr Barbour's office about the source of documents given to him regarding a decades-old scandal over a police bugging operation, codenamed Operation Mascot.

Mr Kaldas was bugged by Mascot, whose team leader was his fellow Deputy Commissioner Catherine Burn.

Mr Barbour has been conducting an inquiry into the bugging scandal for almost three years.

The documents, produced by Mr Kaldas at a parliamentary inquiry earlier this year, suggested Ms Burn had first raised Mr Kaldas' name with Mascot investigators.

But Mr Kaldas admitted to the parliamentary inquiry that when cross examined by Mr Barbour he "did not initially give a candid account of how I became aware of this information".

Earlier, Attorney-General Gabrielle Upton denied to the inquiry that she or her office was responsible for the leak.

Ms Upton said she had "sought relevant assurances" from staff in her office that they did not leak the information.

Director of Public Prosecutions Lloyd Babb also told the inquiry his staff had assured him they were not involved.