A report into the leaking of confidential information relating to a security sweep at the Garda Síochána Ombudsman Commission offices has been unable to confirm the source of the leak.
However, it says it came from a third party attached to the investigation.
GSOC this evening published details of a report it received from senior counsel Mark Connaughton.
In May, Mr Connaughton was asked by GSOC to carry out a fact-finding investigation into how information relating to the sweep may have been disclosed to a third party.
The investigation relates to a Sunday Times article, "GSOC under hi-tech surveillance", which was published on 9 February.
Mr Connaughton reported that he was not able to establish when the Sunday Times journalist received the information, from whom it was received, or the exact nature of the information disclosed.
He said it was possible the journalist had a number of sources, some of whom may have been external.
UK firm Verrimus carried out a security sweep in September 2013 and reported back to GSOC with its findings.
Mr Connaughton said he is satisfied "on the balance of probabilities that the journalist did not have a copy of the confidential report".
He said he believed he had carried out a thorough examination of the evidence within the limits of the type of investigation undertaken.
He said he had received full co-operation from GSOC.
Mr Connaughton said it was difficult to identify what additional information could usefully advance matters, short of obtaining the co-operation of the journalist.
However, he said the journalist had made his position clear on this matter.
Mr Connaughton said third parties may have had information that would have assisted in the preparation of the newspaper article.
He said the type of sweep undertaken by GSOC would have necessitated interaction with "external persons for various technical purposes".
Mr Connaughton said he was "satisfied" that the detail of the article, on the balance of probabilities, was prepared with assistance from some person or persons connected with the security sweep/investigation.
In June, the Cooke Report into reports of unlawful surveillance of
GSOC was published, which found the agency acted in good faith in investigating suspected covert surveillance.
In his report, Mr Justice John Cooke concluded that it was "impossible on the basis of the technical opinions and available information, categorically to rule out all possibility of covert surveillance in the three threats identified by Verrimus" relating to bugging at GSOC.
The Cooke Report also said it was "clear that the evidence does not support the proposition that actual surveillance of the kind asserted in the Sunday Times article took place and much less that it was carried out by members of the Garda Síochána".
