Christchurch Police have amplified their investigation into the disappearance of Yanfei Bao to a homicide probe.
Detective Inspector Nicola Reeves told media "I do not believe she's alive".
"As the investigation has progressed, we've always held grave concerns for her wellbeing, but as the week has progressed, in particular the developments over the past few days, we are now launching a homicide investigation."
Det Insp Reeves said Bao's whānau have been informed of the news "they did not want to hear".
"Our thoughts are with them, and her family are receiving support from police and victim support."
On Wednesday, Police conducted searches in and around the Halswell River, the Greenpark area, Lake Terrace Rd and the New Brighton Rd and Palmers Rd intersection.
"Staff remain at a property on Trevor St conducting a forensic examination."
Reeves said public information is a "vital" part of Police's investation and is appealing for further for information from anyone who saw Bao's car on Wednesday last week.
"Police are interested in the movements of the car between when she was last seen on Trevor St just before 12:30pm and when the vehicle was found on Iroquois Pl. at 10:45pm."
Bao's car is a silver Nissan Dualis with the registration PKT556.
Det Insp Reeves said the Trevor St address in Hornby is of "significant interest" to Police.
"There is significant information and concern that has come from that address."
Reeves wouldn't detail what information has surfaced at the Trevor St address but said "it has certainly helped shape the investigation now".
When asked if Reeves believed Bao was killed between 12:30pm and 10:45pm on Wednesday last week, she replied: "Yes I do".
It comes after a week since Bao, a mother-of-one, was last seen on Vickerys Rd in Wigram last Wednesday.
Police and Bao's whānau have described the real estate agent's disappearance as very out of character and they have deep concerns for the 44-year-old's safety.
On Sunday, a 52-year-old man was arrested and charged with kidnapping Bao, with further charges and arrests not being ruled out.
On Wednesday, Reeves told media Police are keeping an "open mind" in regard to the people who may be involved, but said Police are not actively seeking anyone at the moment.
Bao's car was left parked on Iroquois Pl. Police earlier located one of her cell phones nearly 7km from where she was last seen. Investigators found it in the grass berm along the Southern Motorway.
Investigators have now searched three properties as part of the probe, labelled 'Operation Helo'.
