Gsoc's offices on Abbey Street in Dublin were cleared for late-night counter surveillance sweeps amid concerns about a leak from within its ranks.
Worries about confidentiality arose in May last year as the ombudsman had been involved in high profile investigations and had raised concerns over lack of support from the Garda.
Analysis on the security threats was inconclusive and did not rule out a reasonable explanation for the telecoms issues, said Gsoc chairman Simon O'Brien.
"This report was in my possession only just prior to the Christmas break. I had to think very carefully about the need to report matters to the Justice Minister and other parties," he said.
"At that time, I made a strategic decision not to report what could only be described as suspicious activity that did not meet the threshold of an offence. I have said before in my briefing to the minister and my briefing to the Garda Commissioner that I regret my decision now."
Two threats were identified between September 23 and September 27, while investigations subsequently detected a third.
:: A wireless device in the Gsoc boardroom which had connected to an external Wi-Fi network. Gsoc said its wireless device was password protected but had never been activated and the password was not known.
Gsoc chairman Simon O'Brien said there were concerns about the connection to an external network but there was no question Gsoc's databases or electronic systems were accessed or compromised.
:: The second showed concerns about the security of a conference call telephone in Mr O'Brien's office.
A number of tests were carried out, including an alerting test at 1am in the morning after which the phone rang.
The counter surveillance team said there was virtually no chance this was a wrong number even though attempts to find the number the call came from failed.
Gsoc launched an investigation into suspicions of security breaches at its offices in October.
:: The third was identified in a follow-up visit by the counter surveillance team.
It was sparked by the detection of a UK 3G network which could only have been simulated through a specialist device.
The technology - used only by government level security agencies - recreates a mobile network and picks up or locates phones registered to that network. Once a phone has been connected it can be forced to disable call encryption and leave call data vulnerable to interception and recording.
This threat was located in the vicinity of the Gsoc offices.
A report on the security sweeps found the wireless connection from the conference room to an external Wi-Fi was random with no agent apparent.
It could not repeat the issue with the chairman's phone and did not rule out a call being made innocently to the office at the time of the test.
And on the third threat, it found that the mobile scanner could have been being used lawfully outside the Gsoc HQ or that it was not directed at the building.