Tom Gilmartin, one of the key witnesses at the Mahon Tribunal into planning corruption, has died.
Mr Gilmartin died at Cork University Hospital this morning.
In a statement his family described him as "a much loved husband, father and grandfather" and an honourable and courageous man.
The former property developer gave evidence to the Tribunal that he had given a cheque for £50,000 to former EU commissioner Padraig Flynn.
He began co-operating with the Tribuanl after Mr Flynn appeared on the Late Late Show and denied receiving the payment.
His evidence later led to then-Taoiseach Bertie Ahern being called to give evidence about receiving corrupt payments from developer Owen O'Callaghan.
It also led to damning findings against the lobbyist and former Government press secretary, Frank Dunlop.