Police say they have found "a considerable number of items of interest" relating to the disappearance of Michael McGrath at a Christchurch dump.
The 49-year-old Halswell builder hasn't been seen since May 21.
The search initially focussed on three properties and three motor vehicles.
Over the past month more than 20 officers have turned their attention to Kate Valley refuse centre. Detective Inspector Darryl Sweeney says some of the items "are being examined further."
"Analysis of the many hours of CCTV footage gathered during our enquiries is also ongoing."
A dedicated phone line has been set up for Operation Renovation. Anyone with information should call 0800 findmichael (0800 346 364).
Information can also be provided anonymously via Crimestoppers on 0800 555 111.