An inquiry into the Irish Nationwide Building Society (INBS) is underway.
There are suspicions about how INBS managed its loans and mortgage systems.
The inquiry will look at whether senior staff breached Central Bank rules.
They have been accused of a number of things largely relating to the standards of INBS's loan and mortgage structures.
At the inquiry today were former Irish Nationwide CEO Michael Fingleton and former Finance Director Stan Purcell.
Former chair Michael Walsh was not present, but he was represented by his legal team who brought forward a case for the inquiry to be terminated in relation to him.
Two other former senior lenders were not present.
The inquiry may have to examine more than 110,000 documents.
Irish Nationwide collapsed during the recession and required €5.4bn of taxpayers' money in a bailout before eventually becoming part of IBRC.
It will largely deal with procedural aspects today and could take around 45 days to complete.
Three of the former senior staff deny all claims while two have made no submissions.
The maximum penalty the Central Bank could impose on each person would be a fine of €500,000.