Detectives leading “the biggest murder investigation in Sussex for 15-years” have made a breakthrough in the case.

Grandmother Valerie Graves was found dead with serious head and facial injuries at a house in Smugglers LaneBosham in Bosham, near Chichester, on December 30 last year.

The 55-year-old had been staying at the property while the owners were away over the Christmas period. Now, 10 months after her body was discovered in the bedroom, forensic scientists have obtained a DNA profile for the suspect – identifying them as a male.

Detective Superintendent Nick May, of the Surrey and Sussex Major Crime Team, said the find was a “breakthrough” and police are now asking men from the town to offer voluntary DNA samples.

He added that they are not ruling out having to request DNA from all the men in the village but said that is on the “outer limits” of the police operation and it is “far beyond” their current investigation.

Mr May said: “This is a voluntary process and there are very significant legal safeguards. We cannot use the DNA for anything outside of this case.

“It is something we do use both in Sussex and across the country.

“We have done it in the past and it is extremely labour intensive. There is an element of elimination and we have built up a very detailed picture of who was in Bosham that night.

“This is the biggest murder investigation in Sussex for 15 years and we have a full team of detectives determined to bring it to a positive outcome.

“The DNA sample is extremely significant and helps us see the wood from the trees. There are other lines of enquiry and we have detectives who have travelled the length of the country and have spoken to at least 3,000 people.”

A reward of up to £20,000 is now being offered by Sussex Police and Crimestoppers for information leading to the arrest and conviction of Valerie’s killer.

Anyone with information can contact police on 101 or email 101@sussex.pnn.police.uk quoting Operation Ensign or contact the independent charity Crimestoppers anonymously on 0800 555111.