An investigation into allegations of torture at Lake Alice Hospital is under way following a ruling by a UN committee last month.
The recommendation for an urgent investigation comes from the UN's Committee against Torture, which has upheld a complaint from by former Lake Alice patient Paul Zentveld.
Zentveld was 14 years old when he first was admitted to the hospital's child and adolescent wing in the 1970s, and spent around three years at the facility in Rangitikei.
There, he said he was given electro-convulsive therapy (ECT), was drugged and was placed in solitary confinement.
In its decision the committee recommended the government conduct a "prompt, impartial and independent investigation" into all allegations of torture and ill-treatment at Lake Alice.
Zentveld said the UN findings and recommendations were "a huge win for a lot of people".
"It's a huge benefit for those who have been waiting and for their loved ones," he said.
"We've made history and the rest it up to the government."
Ten years ago police announced no criminal charges would be laid against the head of the child and adolescent unit, Dr Selwyn Leeks, after an investigation involving allegations from 40 people.
Since about 2005 Zentveld has been assisted by Citizen's Commission on Human Rights (CCHR) researcher Victor Boyd.
Boyd said the UN has made it clear what it wants the government to do.
"We continue to do research and provide information to police and also to the Royal Commission, so there's two sort of arms working at the moment, but there's also the other angle of professional accountability.
"The accountability factor would go a huge way towards closure.
"The ball really is in the Government's court to sort that out because of the ongoing neglect of what has happened."
Over the course of his work on Lake Alice, Boyd has spoken to about 40 former patients and five former staff members.
"All the complainants and victims I've spoken to talk about accountability and don't want to have what happened at Lake Alice happen to anyone else again," he said.
"Closure is one major factor and how to do that is to do a proper investigation into what happened."
Boyd said as a New Zealander he feels shame and disappointment for what occurred at the hospital.
"New Zealand should be able to hold its head high to the world and say we don't tolerate electrocuting children, we don't tolerate drugging them for punishment, and if it happens we do something about it so it won't happen again, and that hasn't happened."
Two days after the UN decision was released last month, the Abuse in Care Royal Commission of Inquiry announced it would conduct an investigation into Lake Alice Hospital, and that work was already under way.
Inquiry chairwoman Judge Coral Shaw said commissioners and members of the investigations team had already engaged with a number of survivors of abuse at the site.
"The Royal Commission will use its extensive powers to ensure a thorough examination of what occurred at Lake Alice and the Government's response.
"This will include examining the response of the Police and Crown to serious allegations of abuse."
An Abuse in Care spokeswoman said it's likely the Royal Commission will hold a two-week public hearing into abuse at Lake Alice in late June or early July this year.
However the commission would not make findings "civil, criminal or disciplinary liability", as recommended in the UN decision.
"We will also hold public hearings on other psychiatric institutions and conduct investigations on the experiences vulnerable people had in the care of state or faith-based institutions throughout the course of this inquiry," the spokeswoman said.
The findings will be provided to the Governor General in an interim report later this year and in a final report in 2023.
The government has until the end of March to inform the UN's Committee against Torture about what steps have been taken in response to the findings.
- Additional reporting RNZ