An Organised crime gang believed to have stolen from museums worldwide is suspected of the theft of rhino horns from an Irish National Museum storage facility.
The gang members, with links to the Co Limerick town of Rathkeale, are thought to specialise in stealing the horns.
They struck at the storage facility in Swords, Co Dublin, on Wednesday night. After tying up a security guard, they made off with the eight horns, which have a black market street value estimated at €500,000.
However, the haul may be devalued as the horns are reported to have been coated with arsenic, which was used by taxidermists in the early years of the 20th century to preserve mounted animals.
While investigations are at an early stage, the gang members -- who have links throughout Europe -- are the main suspects.
At least nine members of the outfit have been served with tax demands totalling €9m following a complex investigation headed by Europol.
So concerned were international police forces with the gang's activities in recent years that a special meeting was held in 2011 to come up with a co-ordinated approach on how to tackle it.
Operation Oakleaf was established after gardai asked for Europol's help in gathering intelligence on the criminals, whose network is made up of several Traveller families.
Europol has launched 30 operations in recent months, and 20 investigations are ongoing.
Police forces in Belgium, the Czech Republic, Denmark, Finland, France, Germany, Italy, the Netherlands, Norway, Sweden, the UK, Austria, Portugal, Spain, Switzerland and the US are involved and are liaising with gardai.
Further demands on the assets of gang members are expected after the Europol Criminal Assets Bureau (ECAB) was brought in to the investigation.
The Irish Independent has learnt that gardai are not at this stage investigating anyone living in Rathkeale or local crime gangs following last week's theft.
Members of the gang operate throughout the world year-round and only return to Rathkeale at Christmas, when the town's population trebles.
The black market trade in rhino horns is lucrative in Asia, where they are ground down and used for medicinal purposes.
The four rhino heads with two horns each were removed from public display 18 months ago amid security concerns.