Former Garda commissioner Noirin O'Sullivan has insisted that she did not seek to challenge the integrity of a whistleblower during a private inquiry into his allegations of bad policing.
On day one of her evidence to the Disclosures Tribunal, the retired police chief said she did not instruct lawyers to launch a personal attack on Sergeant Maurice McCabe at the O'Higgins Commission in 2015.
Mrs O'Sullivan said it was about getting to the truth, and not targeting the man.
"I want to emphasise - I have never ever considered Sergeant Maurice McCabe to be malicious," she said.
"I would have absolutely no reason to challenge or impugn his integrity in any way.
"This was never ever about the man.
"This was about the allegations made... and testing the validity and veracity of the allegations."
The Disclosures Tribunal at Dublin Castle is investigating whether unjustified grounds were used in an attempt to discredit Mr McCabe at the private O'Higgins Commission in 2015.
That inquiry examined the sergeant's claims of wrongdoing among gardai in Cavan-Monaghan.
Mrs O'Sullivan was pressed on why lawyers acting for her told Judge Kevin O'Higgins that their instructions in May 2015 were to challenge Sergeant McCabe's integrity and motivation for making complaints about malpractice and corruption in the region where he worked.
When the question was first put to her at the tribunal, the former police chief said: "In terms of Sergeant McCabe's integrity, no."
Disclosures Tribunal chairman, Judge Peter Charleton, highlighted transcripts from the O'Higgins Commission that showed Judge Kevin O'Higgins was first to use the word "integrity" during a legal row in one of the private hearings over how Sergeant McCabe was being treated.
Mrs O'Sullivan also told the hearing that she was never aware of any attempt to undermine Mr McCabe.
"If that was the case I would have said absolutely not," she said.
Mrs O'Sullivan, who retired last September, said there was never any suggestion that Sergeant McCabe had a bad motive for making his complaints.
The tribunal heard that she initially sought an adjournment of the O'Higgins Commission when the issue of her instructions to lawyers first arose on a Friday evening on May 15 2015.
Mrs O'Sullivan had been told by her liaison officer at the inquiry, Chief Superintendent Fergus Healy, that she may be required to appear in person to clarify instructions to lawyers.
"I would very much have welcomed the opportunity to go down to the (O'Higgins) commission - we may not be here now - it would have cleared up all the matters on the day in question," the former commission told the Disclosures Tribunal.
Mrs O'Sullivan said she had a number of other major issues to deal with on that day.
A major security operation had taken place on the same day which led to three anti-terror arrests and a number seizures in connection with a suspected plot to coincide with the Prince of Wales' visit to Ireland the following week.
Mrs O'Sullivan said she would have taken the opportunity to "fulsomely and wholeheartedly" deal with the issue of instructions when they were first raised or on the day that she was there to give evidence.
Earlier, she told the tribunal that she viewed the O'Higgins Commission as a chance to get to the truth.
"I was setting the tone from the top," Mrs O'Sullivan said.
The former Garda boss said it was her imperative that any whistleblower who spoke up would be supported.
Part of the Disclosure Tribunal's terms of reference is considering whether a false and unfounded child sex abuse allegation made against Sgt McCabe in 2006 was used against him.
It is also investigating whether Mrs O'Sullivan's lawyers advised that Sgt McCabe's motivation should be challenged at the private inquiry despite public support for whistleblowers.
The hearing resumes on Tuesday.
