Police are excavating a site at a rural property in Northland where they believe missing woman Bridget Simmonds is buried.
A team of officers have found some items of interest at the property and a person has been helping investigators.
Detective Senior Sergeant John Clayton said about 20 staff were working at the scene today and the excavation process was a complex one, and may take some time.
Police converged on a 20ha block of land on Wilson Rd, Parakao, 40km west of Whangārei on Wednesday after new information came to light which caused investigators to believe foul play was involved in the disappearance of the mother of two.
"Today, police have been concentrating their efforts on searching an area of interest on one of the properties and have reason to believe Bridget may be buried there," said Clayton.
Included in the police contingent was a team of four divers who scoured a section of the Mangakahia river near the block of land, a cadaver dog, Environmental Science and research staff and specialist search teams.
Police also this week opened a dedicated phone line for people to call if they had information that might help with the case.
By late Thursday police announced they had reached a "critical point" in their investigations but due to "operational reasons" would not reveal what that meant.
Simmonds, who was 42 at the time, was last seen at Countdown on February 23 and was reported missing on March 6 after all communication with her family stopped.
Simmonds' mother, who did not want to be named for security reasons, told the Northern Advocate this week that her daughter's disappearance was hard for all the family and it was like living a recurring nightmare.
"I'm hoping they find something ... I don't believe after all this time she is still alive, that's my feeling," she said.
"I hope police can get some answers because for me this is constant. It's like you are living it over and over every day and there's no end to it. It would be a relief to find her so this can come to an end and we can move forward."