The New Zealand Police has been charged with alleged breaches of health and safety laws after the death of a senior gang member in custody, in the first prosecution of its kind.

Taranaki Fuimaono, known as Ardie, had been taken by his family to Auckland City Hospital on the evening of Friday, June 11, last year, complaining of severe abdominal pain and in an agitated state.

He was placed into an induced coma overnight and medical staff who treated him found a bag of methamphetamine in his underwear.

The following day, Fuimaono was discharged from hospital and arrested before being taken into custody around 6pm.

Six hours later, the 43-year-old was found unresponsive in a cell at the Auckland police custody unit.

Efforts to resuscitate him were unsuccessful and he died in hospital a short time later.

His death was investigated by the police, the government health and safety regulator WorkSafe New Zealand, the Independent Police Conduct Authority and the Coroner.

The IPCA and coronial inquiries have yet to be completed.

But the Herald on Sunday can reveal that WorkSafe laid charges against the New Zealand Police last month for alleged breaches of the Health and Safety at Work Act 2015.

The prosecution is against the New Zealand Police as an organisation - not the individual officers involved - as the police are considered a Person Conducting a Business or Undertaking (PCBU) under the legislation.

The charges allege the police failed in their primary duty of care to ensure the health and safety of others, and in doing so exposed an individual to risk of death or serious injury or illness.

If convicted, the maximum penalty is a fine of $1.5 million.

A spokesperson for WorkSafe confirmed details of the charges laid in June but declined to comment further as the matter was before the court.

For the same reason, a spokesperson for Police National Headquarters declined to comment other than to confirm the organisation would defend the charges and had pleaded not guilty in the Auckland District Court this month.

The service card handed out at the funeral of Taranaki 'Ardie' Fuimaono following his death in police custody. Photo / Supplied

At the time of his death, Taranaki Fuimaono was a senior member of the Head Hunters motorcycle gang and about to stand trial on serious methamphetamine charges.

His funeral in Grey Lynn's St Joseph's Catholic Church was attended by hundreds of family members and friends, including mourners from rival gangs in a sign of the respect in which he was held.

The funeral procession of a large cavalcade of motorcycles riding across Auckland was overshadowed by the behaviour of a few, with 16 gang members being charged with driving while disqualified and "sustained loss of traction" - or doing burnouts.

However, the family of Taranaki Fuimaono say he was more than just a member of the Head Hunters.

"He had a reputation within the club…but there was a softer side to him," one of his brothers told the Herald on Sunday.

"Ardie had just become a new dad to a little baby girl, he was looking forward to that. He had taken a different path in life but he was trying to get himself straight, doing rehab."

The brother said his family were pleased that the police are being held to account through the court process, "especially if it means another family doesn't have to go through this".

While the Worksafe prosecution over Fuimaono's death is the first of its kind, concerns have been raised for at least 10 years about the risks to those in police custody who are intoxicated.

All prisoners are supposed to be checked at the start and end of each shift, and at least every two hours during the shift.

People assessed as in "need of care" must be checked at least five times per hour at irregular intervals, while heavily intoxicated people in "need of care and constant monitoring" must be directly observed without interruption.

But while police officers are trained in first aid and custodial management, the level of care required of intoxicated people and those with mental health conditions often exceeds their expertise.

In 2012, the IPCA reviewed each of the 27 deaths in custody over the previous 10 years.

The number one issue identified was "the extent to which the detainees were affected by alcohol and drugs", followed by their mental health.

Nearly 50 per cent were affected by alcohol, and 33 per cent involved drugs.

As well as being a risk factor in itself, the IPCA report found, intoxication can mask other risk factors.

Half of the suicides and 86 per cent of the deaths caused by medical condition involved a person affected by alcohol or drugs.

Another 14 people have died in custody since the 2012 report by the IPCA, according to police figures released under the Official Information Act.

Ten of those deaths involved drugs and alcohol.

One was Allen Ball. The 55-year-old died in the Hawera police station in May 2019 after drinking a large quantity of alcohol and taking painkillers.

Three police officers were charged with manslaughter for failing to provide medical assistance for two hours, but were acquitted after a trial in the High Court at New Plymouth last year.

For several years, the Police Association had been raising concerns about staffing levels and training in the custody suites.

After Ball's death, the police commissioned a wide-ranging review called the Custodial Enhancement Programme, which identified the need for better supervision, training, equipment and facilities.

As of September last year, most of the recommendations had been implemented, including an upgrade to the computer systems used to assess the risk of those in custody.

In regards to Fuimaono's death, Police Association president Chris Cahill said the situation was somewhat different as the staff in the Auckland custody unit were not being prosecuted as individuals.

"We have worked closely with Police to ensure all our members are receiving the best possible advice but Police hold the responsibility to conduct the defence on behalf of their staff in this situation," said Cahill.

"The Police Association has long been concerned about the situation of custodial management. These concerns range from staffing levels, staff training, facilities and the issue of if certain persons should be detained in police custody at all.

"We will be very interested in how these concerns may be considered during this prosecution process."