Ms O’Sullivan was addressing the Charleton Tribunal, which is examining allegations by former Garda press officer Supt David Taylor that he was directed to brief the media negatively on Sgt McCabe by former commissioner Martin Callinan, and that Ms O’Sullivan was aware of this.
Both former commissioners deny this.
The tribunal is also looking at whether Ms O’Sullivan influenced or attempted to influence RTÉ broadcasts on May 9, 2016.
Ms O’Sullivan said she first became aware of Sgt McCabe in 2008 when she received a briefing document on him during her time as assistant commissioner in charge of human resources.
She said that after leaving the post, she never heard anything more about the Miss D allegation in which the DPP directed no prosecution following a Garda investigation.
Ms O’Sullivan said she became aware at some point that complaints about the penalty points system were coming from Sgt McCabe but she could not say when she learned it was Sgt McCabe.
“I do not recall the Miss D allegation being mentioned at any time during that period of time,” the former commissioner said.
She said the appointment of Supt Dave Taylor as press officer “came as a surprise because his background was in the liaison protection section”. But she said it was Mr Callinan’s decision.
Ms O’Sullivan said Mr Callinan was concerned at a Public Accounts Committee (PAC) inquiry into penalty points in January 2014, as it was “unprecedented that sensitive public information could be put in the public domain”.
The tribunal heard that notes taken at pre-PAC Garda meetings referred to “2006 first incident” and “Start McCabe 2006”.
Tribunal chairman Mr Justice Peter Charleton said this must have been a reference to the Miss D allegation made against Sgt McCabe.
Ms O’Sullivan said she had “no recollection of these matters being discussed in my presence at meetings”, and that she might have stepped out of the room when they were discussed.
She said that, when Mr Callinan used the word “disgusting” in relation to whistleblowers at the PAC hearing, she passed a note to him saying he should “withdraw/clarify”.
“The palpable feeling in the room was that it was taken out of context of what was meant by it,” she said.
Ms O’Sullivan said she had no knowledge of alleged comments made by Mr Callinan to TDs John Deasy and John McGuinness or to Comptroller and Auditor General Seamus McCarthy on the day of the PAC meeting.
She said she was unaware of a car park meeting the following day between Mr Callinan and Mr McGuinness until Mr McGuinness spoke publicly about it.
Ms O’Sullivan said she did not give any journalist information about the Miss D investigation. The former commissioner told the tribunal she did not recall seeing correspondence from assistant commissioner Kieran Kenny about a Tusla notification regarding Sgt McCabe in May 2014.
The tribunal has previously heard how the notification wrongly included details of a serious assault from an unrelated case not involving Sgt McCabe or Miss D.
Ms O’Sullivan said she accepted that Supt Frank Walsh gave evidence that he brought the correspondence to her attention, but said she had “no recollection of seeing or reading this file”.
She said that a reply written by Supt Walsh saying that the content of the Tusla report had been “noted by the commissioner” was “actually a pro forma response, almost a template”, and that Supt Walsh would have written that it was “seen and noted” if she had personally read the correspondence.