Police today re-traced the last walk of a dog owner in a bid to jog memories of passers-by to discover what happened in his "missing final minutes".

Exactly a week after George Button was found lying unconscious on a grass verge on a country lane near his home, police re-constructed his fateful final walk with pet dog Laddie in West Rainton, near Durham.

A passing motorist came across Mr Button lying in a pool of blood with severe injuries to the back of his head, in Mark's Lane, at 7.36pm on Monday last week.

Laddie, his black and white border collie, was recovered unhurt nearby.

Mr Button failed to recover consciousness and died in Newcastle General Hospital last Wednesday.

The 53-year-old Sunderland City Council electrician lived with wife, Christina, and seven-year-old daughter, Laura Jane, in St Mary's Drive, West Rainton.

Detectives remain unsure if Mr Button was struck by a passing vehicle or if he was attacked, suffering a blow to the back of his head.

The last reported sighting of him was from a car passenger who saw him standing at the roadside next to Mark's Lane talking to a man with a labrador.

This second man, between 6ft and 6ft 2ins, wearing a heavy coat and dark trousers, has yet to come forward or be traced.

Last night's reconstruction saw a detective taking the role of Mr Button setting off with Laddie from home at around 7.05pm, heading to Hall Lane, over a minor cross-roads and entering Mark's Lane, around 30-metres from the Greyhound pub.

The man leading the inquiry, Detective Superintendent Dave Jones, said Mr Button was seen talking to the other man at 7.20pm, and the call alerting police to the discovery of him unconscious was made at 7.36pm.

"What we hope this exercise has helped to do is fill in the mystery of what happened in those missing minutes.

"That image of someone with a dog walking the exact route taken by Mr Button might have jogged someone's memory and we urge them to come forward with information."

Detectives and uniform officers had a heavy presence in the village during and after last night's reconstruction, asking passers-by if they saw anything last Monday. Anyone with information is asked to contact Durham City CID, on 0191-386 4222, or Crimestoppers, on (0800) 555111.