A man has been arrested in south Armagh in connection with the murder of Robert McCartney in January 2005.
The 51-year-old was detained in Jonesborough this morning and a property there was searched.
He is being questioned at the Serious Crime Suite at Antrim police base.
Mr McCartney, a father-of-two from the Short Strand area of Belfast, was beaten and stabbed after a row at a bar close to the city centre in January 2005.
The 33-year-old died later in hospital.
His sisters, who have accused republicans of covering up the killing and intimidating witnesses, launched a campaign for justice that took them to the White House in the United States.
To date no-one has been convicted.