Former minister for justice Alan Shatter has told the Disclosures Tribunal that dealing with Sgt Maurice McCabe's allegations was like sinking in quicksand.
He said some of the whistleblower's claims were right, some were exaggerated and there was no evidence for others.
Mr Shatter said the sergeant had made allegations that nine individuals had died in accidents due to non-enforcement of fines for non-payment of fixed charge penalty notices.
He said that was incorrect and had been dealt with in an internal garda inquiry, but kept resurfacing.
Mr Shatter said, however, there was no doubt that if Sgt McCabe had not raised his concerns on penalty points, that the issues would not have been dealt with.
He said that in the course of making valid claims, Sgt McCabe made a number of serious allegations on garda corruption and deleting of material on the garda Pulse system, which were not sustained.
Mr Shatter said the former garda commissioner Martin Callinan told him of the Ms D allegations during a phone call.
He said he asked Mr Callinan if there was any background issue he should know about and Mr Callinan told him of the allegation and that there was no basis for prosecution.
The former minister said Mr Callinan speculated that Sgt McCabe was upset with the way the matter was dealt with. Mr Shatter said the conversation was very brief and the former commissioner did not make a big deal about it.
He said he took it to mean that the issue had affected Sgt McCabe and the way he thought he should engage with the gardaí. He said he was never told it was the girl of another member and that she was a child.
Mr Shatter said he did not ever hear the matter raised with him by any politician.
The former minister was also asked about his Dáil apology to Sgt McCabe for saying the sergeant had not co-operated with the O'Mahony inquiry on penalty points.
Mr Shatter said he both stood over the apology and his original Dáil statement.
Sgt McCabe told the tribunal that he was never directed to co-operate with the inquiry.
Mr Shatter said his original Dáil assertion was correct because in circumstances where Sgt McCabe had remained anonymous, he could not have been asked.
Sgt McCabe's lawyer, Breffni Gordon, said that by December 2012, Sgt McCabe's anonymity was gone and garda authorities knew who he was.
Mr Shatter said he understood that Sgt McCabe was not directed to engage, he was invited to engage.
He said he met Ms D at the request of Irish Independent journalist Paul Williams.
The meeting took place in June 2014, a few weeks after he had resigned as minister for justice.
Mr Shatter said he was not in a good place at the time and was traumatised by the circumstances of his departure and he had expected to be vindicated at the time and not condemned.
He said Ms D wanted the original garda investigation examined and he raised the issue as he felt he had a duty as a TD.
Lawyers for the former garda press office Supt Dave Taylor asked Mr Shatter if he believed there was anything inappropriate in the information he had heard from a phone conversation he says he had with Mr Callinan in June 2013 about Sgt McCabe and the allegation against him.
Mr Shatter said Mr Callinan had put the information in a manner that was sympathetically disposed towards Sgt McCabe.
The former minister said it was put in the way that this man was upset, and there was nothing to say he was malicious or seeking revenge.
Mr Shatter said there was no suggestion that the allegation that had been made against Sgt McCabe in 2006 -which the Director of Public Prosecutions had dismissed - should have been prosecuted.
Additional reporting Sinead Morris