Bao was last seen alive on July 19, when she arrived at a house for sale on Trevor St, Hornby, set to show a potential buyer through it.
A week later, her disappearance was upgraded to a homicide investigation.
Since then, police have appeared to focus their efforts on the Halswell River and Greenpark using search experts over ground, water and in the sky.
This morning, there was a heightened police presence at a property at the intersection of Hudsons and Davidsons Rds.
About 20 emergency service staff were there including Fire and Emergency New Zealand (Fenz) and police. They appeared to be focusing on a pond on the property.
Detective Inspector Nicola Reeves confirmed police were in the Greenpark area as part of the ongoing investigation. Fenz was assisting with the search.
A 52-year-old Bryndwr man has been charged with murdering Bao.
The New Zealand Herald earlier revealed the man had only been living in New Zealand for several months.
He was remanded in custody and has interim name suppression. He will appear in the High Court at Christchurch on September 1.
Reeves said police were “committed” to locating Bao and returning her to her family.
