The inquiry would focus on the operation's compliance with the Hazardous Substances and New Organisms Act and the circumstances around the cattle's death, Freeth said.
The Department of Conservation held its own inquiry into the incident and said toxicology results confirmed the animals were killed by 1080 (sodium fluoroacetate).
In October the department announced it would take the "extraordinary step" of having its inquiry independently reviewed by the Waikato Regional Council to provide public confidence in its operations.
During a pre-flight check, staff had noted cows were in an area where bait was to be dropped and notified the farm owners to move the stock, DOC said.
It said the farm owners, Paula and Mark Stone, confirmed the stock had been moved.
DOC said a gate had been pushed over and that may have given the cattle access to the paddock where bait was dropped.
In the days following the cattle deaths, the Stones confirmed they were told to move the cattle and had done so.
However, Mark Stone said he would never have moved his cattle to the paddock where they eventually died if he had known the area he moved them from would not end up receiving 1080.
He said communication from DOC and the Ministry for Primary Industries had been poor and there had been "a complete breakdown".