The Department of Labour says initial inquiries have indicated it should carry out a full investigation into the deaths of two divers in an Auckland lake.
Police are also investigating how Daniel Stoneham, 33, and Tyrone North, 37, died at Lake Pupuke, near Takapuna, during a training exercise on Friday afternoon.
Both the diving school, Helix Training, and its accrediting organisation, will also conduct separate investigations once police have completed their enquiries.
Scuba School International (SSI) is one of the world's biggest diving regulators, and is one of two authorities that administer the teaching of the activity in New Zealand. Helix Training is SSI-accredited.
SSI business development manager Riaan Woest says police are primarily focusing on the men's gas tanks and diving equipment. Other matters, such as diving conditions or negligence, may be looked at later.
A post-mortem is being carried out on Mr Stoneham's body, which was recovered on Sunday. Police are hoping to release his body to family on Tuesday.
A post-morten on Mr North, who was found shortly after the pair failed to surface on Friday afternoon, was conducted on Saturday. His body was released to family on Monday.
Police say they will not release the findings of either post-mortem.
Helix Training has cancelled all classes for the week and will be holding a remembrance ceremony for the pair.
Spokesperson Haydon Allan says the men were both qualified in advanced open water diving, and had completed a rescue diver course. Mr Allan says they have no idea what went wrong.
