The family of an elderly Hamilton woman missing for a week say they become extremely concerned about her safety as each day passes.
Audrey Gibson, 82, was last seen leaving her local hairdressers to walk home to her flat in the suburb of Queenwood last Wednesday.
There have been no confirmed sightings since.
Her granddaughter Angie Tahere says police have now told the family that foul play could be involved.
Ms Tahere says it is out of character for her grandmother to go wandering off and that there has been absolutely no sign of her.
Buses and taxis have been checked and she says it is like her grandmother "has just disappeared".
Mrs Gibson's family say her health and state of mind were good.
Her flat has been locked by police as a possible crime scene but officers who examined it have not found anything out of the ordinary.
A police spokesperson says Mrs Gibson has no history of mental illness and her bank books are still in her house.
The spokesperson says the area is being searched and a boat has again been used to scour the nearby Waikato River and its banks.