A former official of Anglo Irish Bank has gone on trial, charged with conspiring to destroy, mutilate or falsify records of bank accounts connected to Anglo's former chief executive Sean FitzPatrick.

Tiarnan O'Mahoney, 58, of Glen Pines, Enniskerry, Co Wicklow, was Anglo's former chief operations officer.

He has pleaded not guilty at Dublin Circuit Criminal Court to conspiring to destroy, mutilate or falsify books, documents or records relating to eight named bank accounts between 24 March 2003 and 31 December 2004.

The jury was told all eight accounts were, to a greater or lesser extent, connected with Mr FitzPatrick.

Mr O'Mahoney has also pleaded not guilty to conspiring to defraud Revenue.

The trial is expected to hear from more than 30 witnesses and is scheduled to take between four to six weeks.

Prosecuting counsel Dominic McGinn told the five men and seven women of the jury that an unusual aspect of the case was that a lot of the evidence would be by way of documents.

Mr McGinn said the prosecution case was that Mr O'Mahoney had conspired to delete six accounts from the bank's records and to disguise the identity of two further accounts.

He said all eight accounts were connected to a greater or lesser extent with Mr FitzPatrick, who was at the time the chief executive of Anglo. 

He subsequently became the bank's chairman.

Mr McGinn said this was all going on at a time when the Revenue Commissioners were interested in Anglo.

The jury was told that Revenue was investigating Irish banks in relation to bogus non-resident accounts.

These were accounts where the account holders were purporting to live outside the State and would be exempt from Deposit Interest Retention Tax, but actually lived in the jurisdiction. 

Revenue was auditing Anglo accounts in 2003 and had asked for a "snapshot" of all non-resident accounts with a balance of more than £100,000 in 1990, 1995 and 1999.

Mr McGinn said two of the accounts involved in this case were in the name of Mr FitzPatrick's brother in law, John Peter O'Toole. 

He said Mr O'Toole lived outside the jurisdiction but there was an account in his name which it appeared was being used by someone who was not a non-resident. 

The prosecution says there will be evidence that Mr FitzPatrick made it known that he would prefer if the details of his brother-in-law's accounts were not forwarded to Revenue.

Mr McGinn said the prosecution alleges Mr O'Mahoney also communicated this to the bank official with responsibility for dealing with Revenue at the time. 

The account had a balance of more than £100,000 in March 1995 but details were not forwarded to Revenue and Revenue did not audit Mr O'Toole's accounts.

Mr McGinn said another Anglo Irish Bank worker called Aoife Maguire had approached members of the bank's IT team during the audit by Revenue in 2003.  

He said she had asked them to delete accounts from the bank's system.  But he said the IT workers had not deleted them, they had archived them.

When the accounts were recovered from the archive it was found that changes had been made to some of the details of the accounts.

Mr McGinn said the changes reflected a distancing from Sean FitzPatrick and a removal of references to Sean FitzPatrick. 

He said attempts to have accounts deleted or altered were motivated by the connection with Mr FitzPatrick and a desire to conceal information from Revenue.

He said Mr O'Mahoney was part of an agreement to make a deliberate, concerted effort to alter records and to defraud Revenue.

The trial heard from its first two witnesses this afternoon, who gave evidence about income tax and trusts.  

It will resume tomorrow morning.