The police say they are making progress in the investigation into the death of a Christchurch prostitute, although they have yet to determine where she was killed.
The body of Mellory Manning, who was 27, was found in the Avon River on the morning of 19 December. She had been beaten, strangled and stabbed.
Detective Inspector Greg Williams says the police are still seeking the owner of the Falcon XR6 or XR8 that Ms Manning was seen sitting in on the night she was last seen alive. So far 78 of 93 known owners of that model of car have been spoken to.
Mr Williams says the other mystery is where Ms Manning's body entered the Avon River.
Water flow tests will be carried out this Friday in the Avon River, when tidal conditions are the same as those on the night Ms Manning disappeared.
Forensic tests are continuing on a knife and other objects found in the river.
Detectives say Ms Manning's contact book was found in her handbag on her body and they will contact and question all clients listed in the book.