Police will next week search new "areas of interest" in the hunt for Christchurch builder Michael McGrath.

Specialist police search teams will be brought in next week, alongside civilian teams, to search specific areas for evidence in the case.

Detective Inspector Darryl Sweeney said police had consulted an international expert in "locating evidence" in recent weeks.

He said police had found "areas of interest" in the Christchurch region.

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McGrath's family believe something sinister has happened.

The 49-year-old was last seen at his home on Checketts Ave, Halswell, at 4.30pm on May 21, but was not reported missing until the Tuesday. His normal routine was to have dinner with his mother on Tuesdays but he never turned up.

His family found his home locked, and his wallet and cash inside. His phone has not been used since May 21, nor has his bank account.

His 1994 blue Subaru Legacy was parked in the driveway, which was unusual as it was usually in the garage. His push bike was also at the home.

McGrath may have had a 9am appointment on the Monday in Halswell but he "may or may not" have attended.