A man has been arrested over the murder of a loyalist in a busy supermarket car park as his three-year-old son looked on.
Colin Horner, 35, was shot dead by a lone gunman among crowds of shoppers outside the Sainsbury's superstore on the outskirts of Bangor, Co Down, on Sunday afternoon.
The Police Service of Northern Ireland said a 47-year-old man was arrested in Newtownards on Wednesday night and is being questioned at a Belfast city centre police station.
A 28-year-old man detained on Tuesday night remains in custody.
It is understood Mr Horner, from Carrickfergus, Co Antrim, recently relocated to Bangor amid fears he would be targeted in the same loyalist paramilitary feud that claimed the life of his friend George Gilmore two months ago.
Loyalist Mr Gilmore, 44, was shot dead in Carrickfergus in March.
On Monday, Detective Superintendent Richard Campbell confirmed a link between Mr Horner's murder and the long-running Carrick feud between rival loyalists was one line of inquiry.