Criminal charges filed for three former staff members of Lake Alice

Police also found sufficient evidence to charge two other former staff members with wilful ill-treatment of a child. Photo / Bevan Conley

An 89-year-old is set to appear in Whanganui District Court after being charged as police wrap up their investigations into former staff of the Lake Alice Child and Adolescent Unit.

The person has been charged with the wilful ill-treatment of a child - along with two others including 92-year-old former child psychiatrist Selwyn Leeks.

However, those two are medically unfit to stand trial.

The police said that did not mean Leeks was guilty of the alleged offence, just that he could not be charged as he was unable to defend himself in court.

The police investigation into allegations of ill-treatment involving children and young people at Lake Alice Psychiatric Hospital in the 1970s concluded with criminal charges filed against the former staff member.

The 89-year-old is expected to appear in Whanganui District Court on December 14.

The investigation into the long-standing allegations included interviews with former staff of the Lake Alice Child and Adolescent Unit, 63 former patients, and more than 46,000 pages of documentary evidence.

Detective Superintendent Tom Fitzgerald said the conclusion of the investigation was an important milestone for complainants, which is why police first shared the news with them.

"Police acknowledge the enormous impact these events have had on the lives of those former patients who were children and young people at Lake Alice in the 1970s, and the frustration of those who have been waiting for us to complete this investigation," Fitzgerald said.

"This operation involved unprecedented mass allegations, with complex legal arguments and expert medical evidence, so it was vital that we undertook a methodical and meticulous approach with thorough consideration of culpability."

Police have individually updated all former patients who engaged with the investigation since it began in February 2020.

The matter is now before the court and the police said they were not going to comment any further.