The Dail's spending watchdog has decided not to interview the civil servant behind the explosive Ansbacher dossier.
At a private session of the Public Accounts Committee this morning, members decided not to call Department of Jobs official Gerard Ryan.
Mr Ryan had requested to be allowed give evidence in private at the committee.
He was seeking a similar arrangement to that used to allow garda whistleblower Maurice McCabe give evidence of abuses of the penalty points system.
The high-profile committee held an "in camera" hearing for Sgt McCabe last year and although a transcript was never published, the evidence was taken into account in the PAC's damning report on the fixed charge processing system.
However, the committee has decided not to call Mr Ryan after receiving legal advice that he is not covered by protected disclosure legislation.
Mr Ryan had also been seeking for a colleague in the department to be allowed give evidence too.
Two members of the committee, Independent TD Shane Ross and Sinn Fein deputy leader Mary Lou McDonald, dissented from the decision not to call Mr Ryan.
During heated exchanges at the private session, PAC vice chairman John Deasy told Ms McDonald that her naming of individuals listed in the dossier under Dail privilege had effectively ended whatever whatever chance the committee had of investigating the issue further.
The committee decided to wind up its examination of the matter.
Mr Ryan had been seeking to respond to evidence given last month by Revenue Commissioners chairperson Josephine Feehily, who denied a number of allegations he made in the dossier.
Mr Ryan had investigated Ansbacher as an authorised officer between 1998 and 2004.
In a dossier he gave to members of the committee last November, he linked several former government ministers with the Ansbacher offshore tax-dodging scheme.
He also claimed there was political interference in the investigative process.
However, Ms Feehily insisted all leads generated by Mr Ryan were fully investigated.
She also said she had never experienced and political interference in the work of Revenue.