Four men are due in court charged in connection with the murder of Peter Butterly.
Mr Butterly was shot dead outside a pub at Gormanston in County Meath on March 6, 2013.
The detained men were arrested in counties Meath, Cavan and Dublin.
Two other men are currently serving life sentences for the murder of Mr Butterly.
The four men are set to appear before the Special Criminal Court this morning.