The main residence of the man was searched as part of 30 raids in four counties.
In an operation in the planning for months, more than 100 gardaí raided premises in Dublin, Kildare, Cork, and Louth. The operation was conducted by the force’s top organised crime and subversive units.
A number of valuable paintings were removed, along with antique furniture and €50,000 in cash.
Officers took away two firearms — a shotgun and a handgun — as well as computers and documentation.
They searched homes and apartments, along with businesses, including a hotel, as well as accountancy and solicitors offices and an industrial unit.
Garda sources said the search operation was the first phase of what will be a long-term investigation.
The investigation is focused on finding any evidence of money laundering in the businesses raided.
This next phase will involve a forensic audit of financial documents to identify money flows in and out of various businesses — and the source of that income.
The Garda Bureau of Fraud Investigation and the Criminal Assets Bureau, both of which were involved in the searches, will conduct this analysis.
The operation was led by the Organised Crime Unit and involved the Special Detective Unit — which targets paramilitary gangs — the elite and heavily armed Emergency Response Unit, Garda National Drugs Unit, and the National Bureau of Criminal Investigations.
The Garda Air Support Unit and local units also assisted.