Police search and rescue teams in Christchurch have begun examining about 200 properties around a house where a missing teenager was last seen.
Hayden Miles, 16, has not been in contact with his family since his mother pleaded with him to come home on 22 August.
Police have been carrying out a forensics investigation at house in the suburb of Linwood since Friday and are expected to complete it this weekend.
Senior Constable Phil Simmonds says eight groups will be searching vacant and occupied properties for any signs that Hayden was there.
The unoccupied properties will be a particular focus.
Mr Simmonds says the teams will continue door knocking on Friday, but can not say how long the search will take.