By Micheál Lehane

Former developer Tom Gilmartin's allegation that Bertie Ahern had received money from Cork developer Owen O'Callaghan culminated in the then Taoiseach appearing before the tribunal.

Mr Ahern was asked to explain a series of lodgements equivalent to at least €147,000.

He may have told the Mahon Tribunal at one point that it "wouldn't take an accountant more than half a day to work out his income”.

But in fact the Tribunal needed to put the former Taoiseach in the witness box for 13 days to explain his personal finances and the allegation made against him by Mr Gilmartin.

While that allegation spurred the Tribunal to investigate, it was Mr Ahern's private money affairs that required 11 days of questioning.

He had to explain lodgements of around €147,000 into his bank and building society accounts.

Beginning in September 2007, in a 15-minute opening statement Taoiseach he denied that there was any evidence of a $45,000 transaction.

In the first of many clashes with Tribunal Senior Counsel Des O'Neill, Mr Ahern would claim this was a "complete red herring". He said he had evidence to support this, provided to him by banking expert Paddy Strong.

As the crowds attending the tribunal at Dublin Castle grew larger by the day, the Taoiseach would have to explain the role builder Micheál Wall played in the acquisition of his home in Drumcondra.

The Taoiseach was remaining calm too while his labyrinthine personal finances were scrutinised.

But the pivotal Tribunal moment for Mr Ahern came when his former constituency secretary gave evidence on Holy Thursday in March 2008.

Under sustained questioning Grainne Carruth changed her earlier testimony and admitted she had lodged sterling into Mr Ahern's and his daughter's accounts at the Irish Permanent Building Society in Drumcondra.

That turn of events hastened Mr Ahern's departure from office and he stepped down in April 2008.

In June, when he returned to the witness box he clashed again with Mr O'Neill when he sought to explain some funds as the result of some big wins on the horses.

The tribunal lawyer accused Mr Ahern of trying to "hang” his former constituency secretary. He also had to explain a €40,000 loan to his former partner Celia Larkin.

In September 2008, Mr Ahern appeared at Dublin Castle for the last time.

This time he rejected those initial allegations by Mr Gilmartin that he had received money from Mr O'Callaghan to secure the land for the Liffey Valley Shopping Centre.

It marked the end a year of questioning. Before leaving the witness box, Mr Ahern insisted he had done his best to tell the full truth.

The final report of the Mahon Tribunal found that the former Taoiseach gave untrue evidence about the source of over £165,000 lodged in bank accounts connected to him.