MR Sean O'Callaghan, the former IRA terrorist turned Garda agent, has confirmed he will not now be appearing as a witness against another exIRA prisoner fighting deportation from the United States.
Officials from the US Immigration and Naturalisation Service have informed Mr O'Callaghan that they have decided not to call him as a witness against a Tyrone man, Mr Brian Pearson - one of seven Northern Ireland men, previously convicted of paramilitary offences, who is facing deportation proceedings in the US.
The news of Mr O'Callaghan's planned court appearance, at the end of a three week US tour beginning on Saturday, provoked a furious reaction in Irish circles in New York.
Mr Pearson's wife said she was shocked by the reports that Mr O'Callaghan might testify. "I can't believe it and I'm very upset. The INS had spoken of a witness. We thought it would be an RUC man but not someone like this."
Also speaking before the INS decision was confirmed, Mr Pearson's attorney, Mr Martin Galvin, said: "If he ever had any credibility, what there was of it would be destroyed on the witness stand."
Denied a courtroom confrontation between Mr Galvin and Mr O'Callaghan, media interest was turning to next Tuesday's scheduled debate before the House Republican Committee with Congressman Peter King.
It has been confirmed, meanwhile, that the Irish Ambassador to London, Mr Ted Barrington, has again turned down Mr O'Callaghan's request for a briefing on Government policy.