A 30 year old man was detained this morning, Wednesday 1 June, in the Newry area.
Two house searches have also been carried out in the Newry and Rathfriland areas.
The Senior Investigating Officer for the case, Detective Chief Inspector Lee McNevison said: “Mr Carr died in the Royal Victoria Hospital on the evening of Tuesday 17 November 2015 as a result of injuries that he received when he was attacked whilst in his bed at his home in Clogharevan Park, Bessbrook, in the early hours of Monday 31 August 2015.
“The 30 year old man has been taken to Musgrave Police Station in Belfast for questioning.”
A 26 year old woman and a 27 year old man who were arrested in the Newry area on Friday 4 September 2015 in relation to the attack remain on police bail pending further enquiries.