The body of Ruth Hunt, believed to be in her fifties, was found at her home in Exeter.
Ms Hunt, who worked closely with the prison service, is thought by detectives to have been killed two or three days ago. Detectives confirmed that she had been the victim of a "serious sexual assault".
The cause of death was still not known last night. A post-mortem examination is to be carried out at the city's main hospital. A woman neighbour said: "I used to say hello to her in the street. She lived alone at the house and had been there for some time."
Devon and Cornwall police have arrested a man and were holding him in connection with the murder. He will be questioned today at Exeter police station.Reuse content