Six men have been arrested on both sides of the border in connection with the murder of Paul Quinn.
They were arrested early this morning in a coordinated operation in Monaghan and Armagh.
The 21-year-old from Cullyhana in south Armagh was beaten to death by a gang of men in a barn in Co Monaghan in October 2007.
His family has always claimed the IRA was to blame.
This morning gardaí carried out a number of searches and arrested three men.
They are aged in their 20s and 30s, and are being held at Monaghan and Carrickmacross Garda stations.
No further information is being released at this time.
The PSNI says it is supporting the ongoing Garda investigation.
A spokeswoman said PSNI officers would be mounting a number of targeted searches today in the south Armagh area.
The Quinn family has consistently accused members of the IRA of involvement in his death. Sinn Féin has denied any republican involvement.
