Mr Tim Collins, a businessman and friend of the Taoiseach, told the tribunal he briefly called in on a meeting between Mr Ahern and developer Mr Tom Gilmartin in Mr Ahern's offices in Drumcondra in October 1988.
Mr Collins said his own offices were nearby and he would occasionally drop in for a cup of tea. On this occasion he was in the office while Mr Ahern was in a meeting in a back office.
Before leaving he stuck his head in the door to say hello. Mr Ahern introduced Mr Gilmartin, saying "this gentleman" was trying to develop a project at Bachelor's Walk.
Mr Collins said he didn't hear anything that was said at the meeting.
Several years after this, he went to work for the Ambrose Kelly group, he told Mr Hugh O'Neill SC, for Mr Gilmartin.
Mr Gilmartin has told the tribunal that another man was in the office on the occasion he met Mr Ahern, but he didn't see or speak to this person.
