A garda colleague of Sgt Maurice McCabe alleged the whistleblower sexually abused his young daughter.
The Disclosures Tribunal has been hearing evidence from the social worker involved in the case.
This morning they drilled down into the initial allegation of sexual abuse made against Maurice McCabe.
That came from Miss D. A teenager who was involved in social care services since 2005 – with social workers saying she was difficult for her parents, running away from home and self harming.
In 2006 Miss D made a claim of sexual abuse which allegedly happened in 1998 when she was 6 or 7.
The retrospective allegation was that during a game a man held her over a sofa, they were fully clothed but there was humping involved.
Miss D’s father – who was a guard and a colleague of Sgt Maurice McCabe – alleged that Mr McCabe was the man involved.
After looking into it the DPP decided not to prosecute, and social workers decided the case was inconclusive and closed it in 2007.
They said there were no complaints from any other parties against Mr McCabe.
The wider allegations for this tribunal is that the files from this case re-surfaced and that false allegations were made by senior members of the gardaí in a smear campaign against the whistleblower.
The first day of evidence continues here at Dublin Castle this afternoon.