At the time of the tragedy, police said Mitchell had been part of a group of about nine young people, aged from 14 to 19, drinking near Hans Bay.
Paramedics were called about 8.30pm on February 13 to assist two heavily intoxicated teenagers. When police arrived they also found a 17-year-old girl suffering "extreme intoxication" being worked on by paramedics.
Police said the girl was later able to assist them with their inquiries.
A number of people tried to assist Mitchell and the girl before emergency personnel arrived, including local people at the lake and an off-duty doctor, who was staying there overnight.
However, he died while being transported a short distance by ambulance to the waiting rescue helicopter.
Police initially said their focus was on the supply of alcohol to the underage drinkers and the circumstances in which it was consumed.
A funnel and hose was apparently used to consume some of the alcohol, including spirits.
In the days following the death, police said they had already established where the alcohol had been purchased from and by whom.
Acting detective senior sergeant Kieran Tiernan said at the time that a combination of alcohol, including spirits, had been purchased legitimately from a number of Hokitika outlets.
"Our investigations now are rolling in to ... who was supplying it and under what circumstances," Tiernan said.
Norton did not comment on Friday on the details of the investigation but said the case was a reminder to the public that supplying alcohol to young people under the age of 18 was illegal.
It was also vital for everyone to ensure that those around them who did consume alcohol "are doing so safely".
Any further police comment could not come before the conclusion of the court process, she said.
Mitchell Heward's death has been referred to the coroner.
- Greymouth Star
