39 items, including all 26 paintings, worth over half a million euro, are missing from the Killarney House collection.
The revelation is contained in the 2014 report of the Comptroller and Auditor General.
Killarney House was acquired by the State in 1978.
In 2011 an 8.5 million euro restoration programme was announced and it’s expected the house and gardens in Killarney National Park will open to the public next year.
In 1999 the contents of Killarney House were fully catalogued before being removed pending the restoration of the house.
81 items worth 920,000 euro were placed in private storage and in storage at nearby Muckross House.
In October 2012 two paintings, worth 32,000 euro each, that were due to be auctioned were recognised by Department staff as being among the items that had been placed in private storage.
A man was arrested in Shannon in connection with the investigation.
Following that discovery it was found that 39 items worth 552,000 euro held in private storage were missing.
A Garda investigation has been ongoing since 2012 and details of items recovered were requested by the Comptroller and Auditor General.
The Department stated that, on the advice of An Garda Síochána it was not in a position to provide this information.
Following the discovery of the losses, all other Killarney House items that were in private storage were relocated to the Department’s storage facility at the Collections Resource Centre.