Irish Sun journalist Eavan Murray has told the Charleton tribunal she would not allow herself to be used in a smear campaign.
The tribunal is looking at allegations by former garda press officer Supt David Taylor that he was directed to smear Sgt Maurice McCabe. Former commissioners Martin Callinan and Nóirín O'Sullivan deny there was any smear campaign.
The DPP directed no prosecution after a garda investigation into allegations by Miss D in 2006, saying no evidence of a crime was disclosed.
Ms Murray said she did not believe she was ever negatively briefed about Sgt McCabe by Supt Taylor or any garda. She said no garda ever told her that Sgt McCabe was a child abuser.
Ms Murray said she was in contact with Supt Taylor, as shown by telephone records of texts and calls, but said she was not covering the Sgt McCabe story for her newspaper. Her focus was on crime, and she said the penalty points scandal was more of a political story.
Ms Murray visited the home of Miss D in early 2014 to seek an interview. She did not meet with Miss D, but spoke to her parents, Mr and Mrs D.
"When I heard the story I can remember being somewhat surprised at the minor nature of it," Ms Murray said.
"The thought crossed my mind that maybe it was worse and she hadn't been truthful with her parents."
Ms Murray said the D family were concerned that journalist Paul Williams had videotaped an interview with their daughter, and asked her of her experience of people who went public with allegations.
Ms Murray said she was sent by her newsdesk to seek an interview with Miss D after the newspaper learned that the Irish Independent was "going to run a three day special."
"We heard Paul Williams had some huge exclusive that they intended to run in the Irish Independent over a number of days," Ms Murray said.
However, the Independent did not run a story for some time, and when it did, the story was anonymised and did not name Sgt McCabe or Miss D.
"I never wrote about it, and I would never allow myself to be part of a smear, I would never allow myself to be used like that."
Ms Murray said that Mr and Mrs D seemed "exhausted" when she spoke to them, and she felt sorry for them.
Ms Murray said the first time she heard a rumour about Sgt McCabe, in early 2014, it was not from a garda source.
"The person didn't go into a lot of detail about it. It was a very small interaction," Ms Murray said.
Ms Murray said she was shocked when she found out that Supt Taylor had named her to the tribunal as someone who had been negatively briefed.
She said she had met with Supt Taylor and he did not admit that he had given her name to the tribunal, and a few days later she received a letter from the tribunal.
"My fear was he had named me as someone to bolster his own story, and I was correct," Ms Murray said.
Ms Murray said that her child had just been born when she met with tribunal investigators, and "even though they were very lovely, the investigators, it was just very stressful. I found the whole thing very stressful."
Ms Murray said that going to meet the D family directly was "the best check and balance" she could have carried out to check the story.