Police are turning to search experts and geographical profiling in an effort to try to locate missing Wanganui woman Marice McGregor.
They are also hoping her phone can be found, 18 days after she was last seen.
Ms McGregor, 45, was last seen as she drove her red Suzuki Escudo on State Highway 4, the Parapara Highway, about 40km north of Wanganui, on April 19.
Her car was later found near the Lismore Forest, 20km north of Wanganui, but she was not reported missing until seven days later. Her wallet was in the car and her bank account had not been touched.
Significant search and rescue efforts were made in and around the area she was last seen, involving helicopters, divers, dogs and officers on foot, said Detective Senior Sergeant Gwynne Pennell.
Now the investigation team was re-visiting the search aspect to look more scientifically at the areas where she might be, she said.
"Over the eight days since Marice was reported missing to police we have gleaned good information which we can now provide to advisors to assist them with applying scientific methodology," Ms Pennell said.
"Background about Marice, information from friends, family and the public, and timings of telephone activity will allow us to work with advisors to narrow down the possibilities and parameters.
"If harm has come to Marice, the most likely area she will be is the area of the Paraparas. We are working with search and rescue advisor Tony Groome to analyse likely areas, and will then tap into geographical profiling software and expertise to prioritise areas."
Police also now know the type of mobile phone she carried with her and are still trying to locate that phone. She used a Samsung W531 phone which is a flip-top style phone introduced by Samsung about two-and-a-half to three years ago, and it is believed to be black and metallic silver.
Ms McGregor's cellphone was briefly switched on in Feilding, about 80km away near Palmerston North the day after she was last seen.
The phone received some information. Telecom is trying to retrieve the details but that could be impossible as text messages are kept for only 10 days
Police have seized and examined a green Mitsubishi 4WD van seen in the area.
Police spokeswoman Kim Perks said the vehicle's owner, a Feilding man, was co-operating with investigators.
She would not say whether anything had been found in the van but confirmed the man's address was of interest.
