Detectives investigating the murder of Valerie Graves are offering a reward of £10,000 for any information that leads to the arrest and conviction of her killer.
The 56-year-old was found with serious head and facial injuries in Smugglers Lane in Bosham on the 30th December.
She had been staying at the property while the owners were away over Christmas.
Since the murder, more than 200 people have been interviewed and over 100 statements have been taken, but police still feel there are witnesses with more important information that have not come forward.
Detective Superintendent Nick May said, "This was a savage attack, where a significant level of violence was used. We know that a hammer, found nearby in Hoe Lane, was used by the offender and we are seeking the public's help to catch this person before they hurt someone else.
"We particularly appeal to anyone who knows personally, has met professionally, or has a relationship with someone who is violent and who may have used, talked about or threatened violence with a hammer in the past.
"You may have your own concerns or suspicions about this person already, but for your own reasons have not yet come forward.Let me reassure you that we can support you whatever your concerns, but this person must be caught."
Anyone with information should ring 101 or email firstname.lastname@example.org quoting Operation Ensign.