The Republic's Criminal Assets Bureau (CAB) plans to hunt down and freeze Thomas 'Slab' Murphy's assets to recover the £150,000 he still owes in taxes.
The repute d Provisional IRA boss and smuggler was jailed at Dublin's Special Criminal Court for 18 months on Friday for not filing tax returns on his farming income.
However, CAB is not yet finished with the man reputed to be worth more than £46m, but whom Gerry Adams, the Sinn Fein leader, insists is "a good republican".
"CAB has now to move on to the revenue collection process," said an informed source. "Even though he has gone to jail, he still owes the money."
The agency is also to pursue a separate civil case against Murphy for unpaid taxes of up to £4m.
Two of Murphy's closest associates are also under investigation by CAB over suspected oil-laundering activities.
They are now being assessed for what is expected to be a massive tax demand by CAB.
The 66-year-old once claimed he was a simple pig farmer, and now works as a yard man at a factory in Crossmaglen in south Armagh. The Special Criminal Court was told that he survives on a salary of £1,000 a month before tax.
The bachelor farmer is "single", the court was told, and has no dependants. He lives in a modest house on the Murphy family lands straddling the Border in Ballybinaby, Hackballscross, Co Louth.
After his sentencing, Murphy said he did "not own any property at all" and has "no savings".
According to the BBC's underworld rich list, 'Slab' Murphy is reputed to have built up a fortune of more than £46m from money-laundering and smuggling cigarettes, oil and pigs.
He is believed to have done so while reputedly acting as the IRA's head of operations in charge of bombing, and later as its chief of staff.
Security sources believe that Gerry Adams served on the IRA's army council with Murphy.
British security forces believed that 'Slab' Murphy was "head of operations" for the IRA in the early 1990s as Northern Ireland edged towards peace, when Adams, and his colleague Martin McGuinness, were joint deputy chiefs of staff. Adams has denied membership of the IRA, but he has remained loyal to 'Slab'.
Gardai suspect that Murphy was linked to property portfolios in England, Bulgaria and Dubai but were unable to find enough evidence to seize them.
The CAB in the South and its former counterpart here, the Assets Recovery Agency, mounted major operations against the IRA in Manchester and in Louth in October 2005.
The ARA was investigating 250 properties in Manchester and London that it suspected were linked to Murphy. He issued a statement denying that any of the properties were his.
Six months later, police agencies raided the Murphy lands that straddle the border between Louth and south Armagh. Officers found plastic bags in a hay shed stuffed with cash, cheques and drafts totalling hundreds of thousands of pounds.
'Slab' Murphy was presented with a £4.2m tax demand by CAB following the raids. Murphy at first ignored it and then refused to engage with officers at CAB. Only in recent years, did he begin to interact with the agency.
CAB has so far failed to find his supposed fortune. Forensic financial investigators trawled through a warren of bank accounts in Ireland, the UK and the continent but were unable to link funds back to him.
CAB and its counterpart, ARA, also failed to find any evidence linking 'Slab' Murphy to the 250 properties in the UK.
Some of the properties were owned by 'Slab's' brother, Frank.
In 2008, Frank and his wife, Judy, also settled a case taken against them by the Serious Organised Crime Agency in the UK for £450,000, relating to their equity in nine properties in the north west of England.
That same year, the three Murphy brothers, Thomas, Patrick and Frank, agreed to relinquish the €630,000 (£500,000) seized by CAB in the hay shed to the Irish State.
'Slab' Murphy's brothers, Frank and Patrick, reached a separate settlement with the Revenue Commissioners - believed to be in the region of £780,000.
During his trial for tax evasion, 'Slab' Murphy claimed that whatever tax liability he might have had been included in his brothers' settlement with the State. However, the Special Criminal Court judges did not buy that.
Despite relinquishing £500,000 to the State, 'Slab' Murphy had enough wealth left over to fund a lengthy legal challenge to his prosecution for tax offences, taking his case all the way to the Supreme Court.
Those legal fees are estimated to have run to six figures.
The legal fees he incurred in his criminal prosecution are also significant. He was not granted legal aid. He pleaded not guilty and the trial ran for 32 days.
He has also footed the bill for the enormous legal costs arising from his failed libel action against the Sunday Times, which accused him of being in the IRA. The jury agreed.