The first investigation in 1992 was found to have fallen short with evidence while the two others were open when Malcolm died last week, Coster said.
One of those investigations was understood to be sparked by witness statements provided to police from the Royal Commission into Abuse in Care.
“Exactly where those will go now in light of Mr Malcolm’s death… obviously that becomes more challenging. We can’t bring a criminal prosecution but we are assessing the options there,” Coster said.
The moves police make next are of keen interest to one man who claimed Malcolm sexually assaulted him on a number of occasions in 1989 when he was aged 15 and 16.
The man told the Herald he also wanted to know how many others Malcolm sexually abused with one other complaint from 2012 being made public.
Coster addressed the issue after concern voiced by the victim and his family that Malcolm, who died aged 83, had avoided justice because he was a prominent politician with influential connections.
Malcolm was a three-term National Party politician who was first elected in 1975. He was Minister of Immigration and then Minister of Health in Sir Robert Muldoon’s administration.
Coster said: “There was an investigation back in 1992 and that led to the conclusion there was insufficient evidence to proceed with a charge.
“There have been two other active investigations underway from more recent times.”
He said the Police Complaints Authority, as it was at the time, was satisfied with the way the 1992 investigation was carried out.
Coster said police were currently working on “options” around the current investigation while also stating “police is unable to bring a prosecution post somebody’s death”.
However, he did say “our doors are open to people” and “we will provide the support” - the same words the victim had already told the Herald would show police “going through the motions”.
That victim, a man aged 50, said police needed to keep investigating even though it wasn’t possible to prosecute Malcolm because it was likely the only way victims could get the answers they needed.
He told the Herald he wanted to know whether Malcolm was the “Jimmy Saville of New Zealand”, referring to the English entertainer whose death led to disclosure of lifelong sexual violence.
In the Saville case, English police districts continued to investigate despite the entertainer’s death with the intent of identifying criminal conduct connected to his abuse. The inquiry also carried out a fresh review of a decision to not proceed with a prosecution when Saville was alive because it was “unlikely to succeed”.
The victim’s mother told the Herald of her disappointment over the decision not to prosecute in 1992 after police who were investigating raised doubts her son would withstand being cross-examined in court.
“They felt if they took [my son] to court he would have been annihilated by Aussie Malcolm’s legal team.”
In contrast, she said: “We believed we had enough evidence at the time. I could have withstood that on the witness stand. [My son], with the right support, would have been very good too.”
The Herald has approached Minister of Police Mark Mitchell for comment but his office says it would not be appropriate for him to do so - and provided no other reason. His office has also yet to respond to questions over whether he was aware of the allegations against Malcolm.
Clinton Bowerman, a private investigator who is close to the victim’s family, told the Herald he had heard off-colour jokes about Malcolm and abuse when mixing in National Party circles.
David Fisher is based in Northland and has worked as a journalist for more than 30 years, winning multiple journalism awards including being twice named Reporter of the Year and being selected as one of a small number of Wolfson Press Fellows to Wolfson College, Cambridge. He first joined the Herald in 2004.