Ms Adrienne McGlinchey, an apparent informer who played a key role with gardaí in organising hoax finds of explosives in Co Donegal, was a mischief-maker and unreliable source of information, the Morris Tribunal concluded.
The 39-year-old originally made the acquaintance of gardaí in Letterkenny in 1988 when she worked in her family's restaurant.
In 1991 she was arrested under Section 30 of the Offences Against the State Act after gardaí foiled an IRA attempt to plan at bomb at a Border checkpoint. Following a family disagreement she moved to Buncrana where she provided information to the gardaí as an apparent informer.
While she alleged the relationship was one of concerted lies, some senior Donegal gardaí insisted she was a reliable informer who was close to the IRA.
The tribunal concluded that at this time she put together "highly imaginative stories" which had no basis in reality.
"Much of the information provided by Adrienne McGlinchey to the tribunal was mischievous, motivated by a desire to muddy the waters and simply untrue," the report said.
She also engaged in bizarre behaviour which seemed to draw Garda attention to her.
This included being found with items, such as bullets or steel items, which could resemble mortars or parts of rockets to the uninitiated.
The tribunal was satisfied that if any gardaí in senior management had analysed her behaviour at the time, they would have concluded that she was not a genuine IRA informer.
Her relationship with gardaí evolved and during 1993-94 she was the apparent source which led to the discovery of numerous "finds" of explosives.
In several cases the tribunal concluded that the material did not originate with the IRA and that it was in her possession under the control of Det Garda McMahon and Det Inspector Lennon.
The material was to be discovered as a result of information being passed to the Garda from a "reliable source".