Detectives investigating the murder of a North Yorkshire man say they are concerned at the lack of information put forward by the public.

Nearly one month after the body of David Williamson was found at the roadside near his home in Sutton-on-the-Forest, the death remains a mystery.

But in a new potential line of inquiry, detectives are keen to speak to two people seen with a four-wheel-drive vehicle spotted near the scene the day after the body was discovered.

North Yorkshire police stressed that the murder inquiry had not been scaled down and pledged that it will continue.

It is believed that Mr Williamson, 57, was attacked as he walked home from the Star Inn in Huby to his home in Sutton-on-the-Forest on the night of Sunday, March 25.

Medical experts have concluded that he died from a severe blow to the back of the head, probably with a blunt instrument.

A Force spokeswoman said: "Detectives are concerned at the lack of information coming from members of the public.

"Police would emphasise that anyone who has any information at all, no matter how small, should contact us."

One potential new line of inquiry is a four-wheel-drive vehicle seen between 9.45am and 10am on Monday, March 26 in a field next to the graveyard at Sutton-on-the-Forest.

A witness has described two people being with the vehicle, one of whom was a man with heavy-framed black-rimmed glasses.

The spokeswoman said: "It may be there was a good reason for the vehicle to be in the field at that time but detectives want to eliminate it from their inquiries."

A 27-year-old local man who has been arrested and questioned by police remains on bail.

Updated: 08:39 Friday, April 20, 2001