Missing real estate agent Yanfei Bao 's body has not been found, but police do not believe she's alive

The 44-year-old Harcourts agent was last seen on Wednesday last week.

Detectives and the dive squad are searching multiple areas in the greater Christchurch area, including the Halswell River, a home in Hornby, and near the Avon River in New Brighton.

Herald reporter Sam Sherwood says police won't go into detail about how they can rule it a homicide investigation without finding a body, other than to say more information has come to light in the past couple of days.

Police have not ruled out further charges for a 52-year-old man, who's in custody on a kidnapping charge.