For more than two months, Fianna Fail's Ivor Callely was evasive about his expenses claims.
It was 2010 and I was examining claims made by TDs and senators - one stood out.
Callely was paid almost €3,000 in one go in November 2007, under a system that allowed TDs to claim €750 for mobile phone expenses every 18 months.
How had he submitted €3,000 when the limit was €750? Callely refused to answer calls.
I persisted and he eventually supplied a short explanation that it was the payment of back expenses.
In the preceding years, Callely served as a minister, in the Department of Health and the Department of Transport. More digging revealed the departments paid for his phone expenses.
Callely again refused to respond to questions and simply stuck to his story.
Frustrated, I submitted requests under the Freedom of Information Act for the actual documents that Calley used to vouch for his expenses.
When the phone invoices that had been submitted to the Oireachtas by Callely arrived on my desk, it was clear that something was wrong. The invoices used the pound symbol and the phone number for the company invoiced was one digit too short - a seventh digit was added to the Dublin code in 1994 .
The company, Business Communications, went bust in 1994 - eight years before the date on the first phone invoice.
Two contained the incorrect spelling of the word received, branding it 'recieved' instead, and all came to almost exactly €750 - the maximum allowed under the scheme. They were also dated almost exactly 18 months from each other - the expense renewal period.
The liquidator of the company told me it did not trade after 1994 and one of its directors told me he had never sold a mobile phone to Callely.
It was clear that the invoices were forgeries. I tried to confront Callely, but he was impossible to contact after the first email.
His secretary said he was not getting emails and repeated that his expenses were paid by the relevant authorities.
Even after the investigation was published, the evidence was clear and Callely had been arrested, he continued to plead his innocence.
It wasn't until March this year that he finally accepted what he had done, pleading guilty in court.