The Garda Ombusdman Commission has been unable to identify who leaked claims the organisation was being bugged, to the press.
The commission launched an investigation in February after The Sunday Times Newspaper reported GSOC had undertaken a security sweep over concerns that its offices were under surveillance.
A Senior Counsel has now examined all the documentation relating to the story, including a review of CCTV footage and all e-mail correspondence. Current and previous staff were also interviewed and an outside firm was contracted to provide technical analysis of mobile phones.
The journalist who wrote the story declined to cooperate.
The findings of Senior Counsel Mark Connaughtons's report are published today. He says he was unable to establish individual responsibility for any disclosure.
No further action is to be taken.
The report concludes that it is difficult to identify what additional information could usefully advance matters, short of obtaining the co-operation of the journalist in question.
GSOC says it has has forwarded a copy of the report to the Minister for Justice & Equality, Frances Fitzgerald.
The Organisation adds it does not intend to publish the report because 'it contains personal data which is impossible to redact effectively.'
