The protected witness David Rupert has told the Special Criminal Court that he was handed an envelope containing $10,000 in cash by a prominent Republican.
Mr Rupert said Joe O'Neill asked him to carry the money from Dublin to Bundoran for him because he did not want to get stopped at a checkpoint.
He also said he checked the envelope to make sure that it was cash before taking it.
The money was handed over at a Dublin function by a man from Boston for Republican Sinn Féin.
Mr Rupert has also being outlining how he became a close associate of republicans in Ireland.
He said in June 1996 the FBI gave him $8,500 to lease and run Drowes Bar and the nearby caravan park in Tullyhane in Co Leitrim.
He ran the bar to gather intelligence for the FBI on republican figures in Ireland.
He told the court Joe O'Neill asked him to set aside ten or twelve beer kegs and then he showed him a hand sign which in republican circles meant explosives.
He said republicans use hand language when talking about shootings and bombings.
He also told how he met the former head of the Garda Crime and Security Division, Dermot Jennings, and that when he asked the Assistant Commissioner about money he was told 'the Gardai don't do that'.
He said he got no money from the Gardaí although he was offered mileage but he thought that this would only be ten pounds and let it slide.
He also said he turned over the serial numbers of the beer kegs to Assistant Commr Jennings and because they could be used for explosives he got a steel scrapper to take the rest away.
He was giving evidence in the trial of Michael McKevitt, who denies being a member of an illegal organisation and directing terrorism.
