Defence lawyers for convicted republican Michael McKevitt have claimed that gardaí investigating the Omagh bombing did not adequately investigate the credibility of FBI agent David Rupert.
McKevitt is one of five men being sued by relatives of the victims of the Omagh bombing in 1998.
Mr Michael O'Higgins SC for McKevitt was questioning Superintendent Diarmuid O'Sullivan in relation to five statements Mr Rupert gave to gardaí during the investigation into the bombing in 2001.
Mr O'Higgins said Rupert's statement was 'a tissue of lies' and described him as a 'fraudster, drug smuggler, people smuggler and a confidence trickster'.
Mr Rupert's evidence was key to the 2003 conviction of McKevitt, who was jailed for directing terrorism. McKevitt has always denied knowing Mr Rupert.
The prosecution in this civil action are seeking to establish that McKevitt was the Real IRA leader who carried out the 1998 Omagh bombing.
Superintendent O'Sullivan said it was not up to the gardaí to investigate matters relating to alleged fraud committed by Mr Rupert in the US.
But he said he believed 90% of Mr Rupert's evidence in relation to the activities of dissident republicans had been substantiated.
He said three judges in the Special Criminal Court and in the Court of Criminal Appeal had tested the credibility of Mr Rupert's evidence.
Earlier, the court heard the address of a vocational school in Donegal was given to Mr Rupert as a location to ship weapons and ammunition to.
Supt O'Sullivan said Mr Rupert had given gardaí a business card, which he said he was given from a well known republican Joe O'Neill .
It had 'Kathleen Askin, Vocational School, College Street, Ballyshannon' handwritten on the top.
Supt O'Sullivan said that this was the address that David Rupert was given by Joe O'Neill to ship military supplies from the US for the continuity IRA.
The hearing, which is taking evidence in Dublin, was told that Mr Rupert passed the evidence on to gardaí who were probing terrorist activity on both sides of the border.
