Detectives will return to the scene of a grisly unsolved murder today, one year after a grandmother was mysteriously killed while she house-sat for friends.

Artist Valerie Graves, 55, was found bludgeoned with a claw hammer in a ground-floor bedroom in Smugglers Lane, Bosham, near Chichester, on December 30 last year.

The culprit has not been caught despite a large investigation.

More than 9,500 people have been interviewed, a £20,000 reward has been put up, a BBC Crimewatch appeal has been made and a limited DNA match of a suspect has been yielded.

Exactly one year on from the brutal killing, police will return to Bosham today and tomorrow to speak to residents and visitors in an attempt to force a breakthrough.

Detective Superintendent Nick May, of the Surrey and Sussex major crime team, said: ''We need the public's help to catch this person before they hurt someone else and to get justice for Valerie and her family.

''There will be police officers in Smugglers Lane and Bosham Lane, Bosham, on December 29 and 30 from 10am to 4pm who residents and visitors can speak to if they have any information.''

Ms Graves was murdered as she house-sat with her sister Jan, mother Eileen and her sister's partner, Nigel Acres, while the property's owners holidayed abroad over Christmas.

Last week, Ms Graves's family spoke of their difficulty in coming to terms with the death.

A post-mortem examination revealed Ms Graves suffered significant head and facial injuries. A 22-year-old man arrested over her murder was later freed without charge.