Health and safety experts believe safety procedures would not have stopped a man from climbing on the ledge of the 54th floor of Auckland's Sky Tower.
The man paid to do the tourist attraction, the SkyWalk on Saturday afternoon, but walked to the railing instead where he then threatened to jump off.
SkyWalk says the man scaled a safety fence to get to the ledge and all correct safety procedures were followed by staff. The attraction has closed while a full investigation takes place.
The New Zealand Institute of Safety Management promotes health and safety in the workplace. National manager Tony Rigg believes SkyWalk did everything it could in what was a difficult situation.
"In any investigation, there is always a lot to what's happened. And if a person like this is determined to do something like this, he obviously had a mindset to do it.
"He might have come across as quite casual and quite normal, and then just suddenly with somebody not looking just very quickly took a step out the door, or something like that."
Mr Rigg expects the internal investigation by SkyWalk, which he says has a very good reputation for health and safety, will be thorough.
Meanwhile, Labour Party says the Government's health and safety officials must investigate the incident to stop it from happening again.
The Waikato District Health Board said on Sunday the man is now back with psychiatric services and an investigation is underway into the circumstances of his departure from a treatment centre in Hamilton.