Former deputy police commissioner Nick Kaldas went back on his evidence about how he ended up with damning documents detailing a controversial bugging operation after his source outed himself.

After a four-year investigation, titled Operation Prospect, into a controversial police bugging saga stemming back to the late '90s, the NSW Ombudsman finally released its findings on Tuesday.

Among the issues detailed in the long-awaited report was how one of these targets – Mr Kaldas – ended up with restricted documents revealing why he was pursued by the controversial Taskforce Mascot, which was the name of the bugging operation.

The reports outlines that Mr Kaldas may face charges for giving misleading testimony about how he received this material during a Operation Prospect hearing.

The allegation comes down to an exchange between Kaldas and the Ombudsman during the hearing in September 2014.

Mr Kaldas initially gave evidence that his documents came via anonymous bundles he received at work and denied getting such material from NSW Crime Commission staff, including its solicitor John Giorgiutti.

"And can we take it from what your evidence has been today that none of these people [from the Crime Commission] gave you any documents?" the Ombudsman asked.

Mr Kaldas: "Yes, that's the case."

Pressed further, Mr Kaldas later conceded Mr Giorgiutti showed him confidential documents, including an affidavit for a telephone intercept warrant application targeting the home of Mr Kaldas' former wife.

"It's a very clear question: you were provided with documents by him that were confidential documents and you took them away, didn't you?" the Ombudsman asked.

"Yes, I would have," Mr Kaldas replied.

"So why did you not disclose that when you were asked questions repeatedly earlier today about what information was provided to you by people, that was confidential and relevant to these matters?

"I think in some ways I blocked it out of my mind."

A month before Mr Kaldas gave this evidence, Mr Giorgiutti had told the Ombudsman he was the source of those documents.

In evidence to the Ombudsman in August 2014, Mr Giorgiutti explained how his concerns about the appropriateness of Mascot's targeting of Mr Kaldas formed.

He said he discovered the informant – known as "Sea" – who made police corruption allegations and was critical to the Mascot investigation, didn't volunteer information about Kaldas.

Instead he was asked by investigators "What do you know about Kaldas?"

"So then I realised, 'shit what have we done here?'" he told the Ombudsman. 'We've crucified this bloke'."

Mr Giorgiutti described the situation as a "f--k-up" and explained that he didn't know if he could trust Mr Kaldas or if he would use the documents against him.

"So if you understand, I was basically in charge of this finding out what happened to protect the state," he said.

"And I need him to help me, I need others to help me and I've got to sort of play – you know, I was like in an undercover role so to speak..."

"...he's not stupid; I mean, he was undercover himself."

Mr Giorgiutti said all his disseminations were lawful, but the Ombudsman's report found he had no authority to release the documents to Kaldas and his conduct was unreasonable.