A MAN knocked unconscious while walking his dog died in hospital yesterday.

And late last night, police appealed for a man seen talking to him about the time of the incident, to come forward.

George Button, 53, of West Rainton, near Durham City, had been on a life support machine in Newcastle General Hospital since Monday night.

Family members including his wife, Christina, were at his bedside.

Police said they were still keeping an open mind about whether Mr Button, a Sunderland City Council electrician, was the victim of a hit-and-run driver or an assault.

His injuries were possibly caused by a single blow on the back of his head.

Mr Button had taken his 14-year-old border collie, Laddie, for a walk in Marks Lane, a country road on the outskirts of the village, at 7pm on Monday.

A motorist found him lying unconscious in a pool of blood half an hour later.

Detective Superintendent Dave Jones, of Durham CID, said last night: "A passenger in a car travelling along the lane at 7.20pm saw Mr Button talking to another man.

"It's imperative this man comes forward as quickly as possible, he may be able to provide vital evidence."

The man is described as six foot tall, wearing a heavy three-quarter-length dark coat, with dark trousers. He was with a dark labrador-type dog.

Mr Button, who worked at a depot in Houghton-le-Spring and had a seven-year-old daughter, Laura Jane, was a regular dog walker.

Anyone who saw him or has information about the incident is asked to call Durham CID, on 0191-386 4222, or Crimestoppers on (0800) 555 111.