A former policeman has become the second person to die after alleged stabbing and hammer attacks on the New South Wales south coast over the weekend.

Mick Horne, 54, died in hospital on Sunday afternoon after he was allegedly attacked by 20-year-old Murray Deakin in Bega on Friday.

Deakin, 20, allegedly attacked his grandparents at their home in the town, killing his grandmother and seriously injuring his grandfather.

He fled the scene in their car before allegedly striking the retired traffic policeman with a hammer and stealing his car.

After being pursued by police he crashed the car and ran into nearby bushland before he was arrested and taken to hospital for a mental health assessment, police said.

Horne retired as a senior constable in 2009 after serving at Bega traffic and highway patrol command, NSW police said in a statement on Monday.

“The family would appreciate privacy at this time,” the statement read.

Deakin was charged with two counts of murder in Batemans Bay local court on Monday. He did not apply for bail and it was formally denied.

Deakin had been living with his grandparents in the weeks before the alleged attack.

His grandmother, Gail Winner, 61, did not survive the alleged stabbing and her husband Thomas Winner, 71, was still in hospital in Canberra on Monday where he was in a critical condition.