A man has been arrested on suspicion of murder after the death of a dog walker.
Anita Rose, 57, was found seriously injured by a member of the public in Brantham, Suffolk on 24 July and died four days later in hospital.
Detectives said a 55-year-old man had been detained in Ipswich and was being questioned.
Three other people were previously arrested and bailed in connection with the incident.
A Suffolk Police spokesperson said: "The man is currently being questioned at Martlesham police investigation centre, where he remains.
"Specialist officers are supporting Anita’s family and keeping them updated on the investigation.
"Anyone with any information that may assist with this inquiry is asked to contact the major investigation team."
Ms Rose had left her home at about 05:00 BST on 24 July and was discovered unconscious by a member of the public at 06:25 BST near the Anglian Water sewage works and railway line off Rectory Lane in Brantham.
Villagers reported seeing an increased police presence in the area on Thursday, including a helicopter and dog units.