Auckland City Council now has control of the scene at the Southdown freezing works in Penrose after a major fire.
The council is to begin overseeing a cleanup of the site which contains asbestos.
The Fire Service finally left the works on Sunday after bringing fresh hotspots under control on Saturday. The fire started in a derelict coolstore at about 6pm on Saturday, 20 December.
Arson remains a possible cause, but the Fire Service says any evidence may well have been destroyed.
Newly contracted security staff have been told to contact police immediately if anyone is found on site.
Southpark Corporation, which owns the works, says the cleanup will be a lengthy one and will cost millions of dollars.