Gardai investigating the murder of Paul Quinn at Tullycorra, Castleblayney, in 2007 have arrested a man in his early 20s.
Quinn (21), from Cullyhanna, Co Armagh, was beaten in a shed by a gang armed with cudgels near Castleblayney, Co Monaghan on October 20, 2007.
The investigation into his death is being run jointly by the PSNI and the gardai.
His family have long alleged paramilitary involvement in the young man's death.
Quinn died after a sustained beating by up to 15 masked men on a remote farm outside Oram, near Castleblaney.
Gardai believe the beating could not have been carried out without sanction from local IRA leaders.
As part of their investigations into the murder, gardai sought to establish if Quinn was the driver of a diesel lorry that was found abandoned and burnt out in Lisburn two weeks before the attack.
The latest arrest was in Dromad, Co Louth yesterday morning. The man was detained at Carrickmacross Garda Station.