Files were passed on to higher authorities.
A Garda spokesperson said: “In 2010, a formal Garda investigation commenced, under the direction of superintendent, Thomastown, as a result of disclosures made by a social worker with the HSE, which provided details of possible sexual abuse, emotional abuse and neglect, by her foster parents, of a 26-year-old vulnerable female, in the care of the HSE.
“Resulting from the investigation commenced under the direction of superintendent, Thomastown, an investigation file was submitted in November 2012 to the law officers.
“Following on from this investigation and as a result of other concerns being identified, including those relating to the original vulnerable person, as well as other service-users who were placed with the original foster carers, a further investigation was commenced under the direction of the divisional officer, chief superintendent, Kilkenny/Carlow.
“That investigation remains ongoing, while, at this time, a number of investigation files have already been submitted to the law officers for consideration.”
Separately the HSE said staff who worked on the case could not have been identified to Tusla earlier.
A spokesman said: “The HSE was precluded from informing Tusla due to ongoing inquiries and investigations being undertaken by An Garda Síochána.”
He said: “A HR assessment has been undertaken in relation to the staff members who remain in the employ of the HSE. As confirmed at the press briefing earlier today, there are no issues arising at this time in relation to the current roles of these individuals.
“We are now moving into the next phase of the HR process which involves utilising the HSE HR policies to progress matters without delay.”
He added that there was “a period of protracted legal process into certain matters” prior to publication of the reports.
Tusla, in a separate statement, said it had met with the staff concerned to advise them of the publication of the reports and had also completed an initial HR review process.
The agency also confirmed there were six Tusla staff referred to in the reports.
A Tusla spokesperson said: “We are currently examining the reports published today and will further review the individual staff involvement in the case at the time. If any issues emerge as a result of this review, further HR processes will be invoked, as necessary.
"We are actively liaising with An Garda Síochána to ensure that our own internal review processes do not impede their separate, ongoing investigation. Additionally, we will fully co-operate with the forthcoming commission of inquiry.”