A man in his 60s is in a critical condition on a life support machine after he was attacked a week ago.
It is understood Mr Doherty has been assaulted before
Francis Doherty was found at about 0100 GMT on Sunday 16 March at a house at Commons Road in Ballykinler. He had suffered a serious head injury.
Police were called to the scene after reports of a disturbance. Two men were arrested but were released on bail.
Police in Downpatrick are appealing to anyone who knows anything about the assault to come forward.
Mr Doherty's brother-in-law Jim Campbell said it was not the first time he was assaulted in his own home.
"He has had trouble before, because his windows have been replaced three or four times before," he said.
"The last time, his windows were not replaced from before Christmas.
"His house has been vandalised on a number of occasions. He got a beating before. His house was broken into and he got a beating in his own bed."