The family of a man who died in custody at the Hāwera police station last year say they were stone-walled by police when they tried to find out what happened to him.
Three officers have now been charged with manslaughter over the death in June 2019.
It's alleged the officers failed to provide the 55-year-old, who the Coroner has ruled cannot be named, with necessary medical care.
He had been arrested for assault following a callout to a family harm incident at a Hāwera address.
An older Australian-based sister of the man - who also cannot be identified - said the family's attempts to find out what led to her brother's death drew a blank.
"They spoke to us to start with. One phone call. And they told us to ring back in a week which we did and no one would speak to us.
"We actually went through the complaints department, I can't remember what it's called, because the police wouldn't talk to us. There's been a lot of emails and phone calls and everything to try and get this resolved."
The sister said the Independent Police Complaints Authority had been wonderful to deal with.
"Now every time there's a development they let us know."
The sister said it was her understanding that her brother - who was described by police as being intoxicated when arrested - was unresponsive when he arrived at Hāwera police station.
"Now to me if someone is unresponsive you would ring an ambulance or seek medical attention but they didn't.
"They failed in their duty of care ... it's a fact that our brother could still be alive."
In the original 2019 media release about the incident, the police said the man was discovered unresponsive after a routine check.
Alcohol lay at the heart of the domestic dispute which set the unfortunate sequence of events that lead to her brother's death, the sister said.
She hoped her brother would get justice through the courts.
"I'd like to see them charged properly and sent to jail."
The woman said she hoped the police methods for dealing with vulnerable people in custody might improve through the process.
"They have a duty of care. It doesn't matter ... I'm a nurse and I think that for anyone who would be unresponsive that you would seek medical advice."
The police response to families could also be improved, she said.
"I filled out all the paper work saying I was next of kin, his sibling. I sent off all my proof of everything. Now I should've been told by them what was going on. We're in Australia so it's very hard for us. They should've thought of us as well."
The woman said her brother was a "bit of a shit growing up" but very family orientated.
"He loved his family. Brothers and sisters. His children.
He was loving family man. He loved his family, especially his children, they were his life."
In a statement, IPCA said it was the police who referred the incident.
"This matter was referred to us by police as is required by statute whenever there is a death or serious injury that has occurred in the course of interaction with police. The authority then independently investigated the matter and liaised with family throughout that process."
Police, via an emailed statement, said they were unable to answer questions about how complaints about the incident were handled.
"Anyone who makes a complaint to police has the right to privacy."
The three officers, who have been stood down from their duties, will reappear in the High Court at New Plymouth on 26 June.