The 21-year-old Dunedin student attacked in her home has short-term memory loss and has been unable to help police hunting her attacker.
Detective Senior Sergeant Steve McGregor said the woman returned to her Waverley home last week after a week in hospital being treated for a head injury.
Police had spoken to her, but she had short-term memory loss and was unable to help with inquiries into the October 14 attack.
Forensic tests on items from the home, including the weapon used, still had to be completed.
Police hoped to interview the woman again.