Vikki Thompson, 30, had been fighting for her life in hospital since she was found by neighbours last weekend.
Detectives in Oxfordshire investigating the attack yesterday switched their efforts to a murder inquiry.
Mrs Thompson was found with a fractured skull by a railway line near her home in the Cotswold village of Ascott-under-Wychwood last weekend. She died yesterday morning as a result of her injuries.
Police believe her attacker struck in a wooded track and dragged or carried her across a field close to a railway line. It is thought she put up a desperate struggle with her assailant who bludgeoned her with a rock.
Her husband, Jonathan, a 30-year-old computer software salesman, and neighbours in the village became concerned when she failed to return from walking the family's dog last Saturday.
A team of 50 murder squad police was drafted in to the village as the mystery deepened over the motive for the attack.
Detective Superintendent David Blair, leading the inquiry, said yesterday: "I don't believe the motive was robbery and there is no evidence of sexual assault so far."
Police will be examining Mrs Thompson's private life in case her killer is someone she knew.
Mr Thompson was by his wife's bedside at the John Radcliffe Hospital, Oxford, when she died. The couple have a son aged seven and a daughter aged five.Reuse content