A new call has been made for charges to be laid over alleged abuse of young people at Lake Alice Psychiatric Hospital in the 1970s.

Former patients have told the Inquiry into Abuse in Care that they were subjected to massive doses of medication and the use of electroconvulsive therapy as a punishment.

One of them, Leonie McInroe, was wrongly diagnosed by the head of the adolescent unit at the time, Dr Selwyn Leeks, as borderline schizophrenic.

McInroe spent 18 months at Lake Alice Hospital in Rangitikei, going in at the age of 14.

The Crown has acknowledged the wrongdoing and settlements have been made with some former patients.

Citizens Commission for Human Rights director Mike Ferriss said Leeks was the main person of interest, but others could be equally culpable.

"These people are not above the law... they should never be protected by the Crown where potentially criminal acts have taken place," Ferriss said.

A police investigation more than 20 years ago did not result in any charges being laid.

Ferriss said he believed only one former patient was questioned at the time.

A new police investigation is underway, following information from the Inquiry into Abuse in Care, said director criminal investigation Detective Superintendent Tom Fitzgerald.

"As these investigations are active, no further information can be released at this time," Fitzgerald said.

"Police are planning to have the first phase of the investigation completed by the end of the year.''

Ferriss said about 40 people had spoken to police so far.

''I think the police will find the evidence is there - we know it's in the medical records," Ferriss said.

''Some of the records actually state, 'running away', 'electric shocks to the legs', things like this.

"Electric shocks to the genitals is a form of sexual abuse. We know these things happened, they are not just stories.''

The Royal Commission into Abuse in Care will hold its own inquiry into Lake Alice Psychiatric Hospital in June next year.

-RNZ