A detective has indicated he may use the findings of a coronial inquest to reinvestigate three or more suspects following the suspicious death of a woman at an Auckland hospital.
Heather Bills, 64, died at Middlemore Hospital on January 2, 2013, six weeks after she was badly burned in an explosive house fire.
On the evening of November 22, 2012, she was pulled from the blaze after neighbours braved the inferno to rescue her from an upstairs room of her Orakei home in Auckland.
She was then treated at the National Burns Centre and intensive care as her condition improved.
However, on Boxing Day, 2012 her health quickly deteriorated as she developed low glucose levels.
She suffered a massive hypoglycaemia-related cerebral injury which resulted in an irreversible brain injury and she died on January 2, 2013.
It became clear that her death had been a result of higher levels of insulin in her body.
A coroner's inquest is being held over the next two weeks into Bills' death before chief coroner Judge Deborah Marshall in the Auckland District Court.
Investigating officer, Detective Senior Sergeant Ross Stephen Ellwood, said the grandma's death was the first and only one of its kind in New Zealand.
Bills was not diabetic and had not been prescribed insulin, the court heard.
Ellwood suspected she had been administered insulin by medical staff.
"I have my own view as to whether [Bills] was injected or not, but my view is not important, it's what I can prove in court," he said.
"I think she was injected."
However, Ellwood conceded there was an element of doubt, based on expert medical opinion, as to whether she was administered vials of insulin.
Police were contacted on December 31, 2012 and advised that there was suspicion around Bills becoming so rapidly unwell.
As part of police inquiries, CCTV from the hospital was taken, and swipe card records obtained, however, no suspicious records were found.
"Everyone who had care of [Bills] was interviewed," he said, adding none admitted they had administered insulin.
However, "on the balance of probabilities", Ellwood said Bills may have been injected with insulin, or given it through an intravenous line.
There were three suspects, all medical workers, as part of the criminal investigation, he said.
"We're looking at someone working in a hospital, potentially causing the death of a patient, and we can't have that," he told the court.
Michelle Maher, Bills' daughter, told the court that "without the brave actions of her neighbours" her mum's life would have ended inside her house.
No drugs or alcohol were found in Bills' system on admission to hospital.
"My mum had, however, suffered a long and difficult mental illness, highly functioning and successful from the outside yet unable to enjoy the simple pleasures of life many of us take for granted."
She said her mother had "a long road to physical and emotional recovery ahead but my mum was alive".
"Her low blood sugar test results were missed by the medical team on two separate occasions before finally being noticed over five hours from onset of symptoms and three hours after the alarm was first raised by nursing staff.
"I sat bedside as my mum trembled, groaned and gasped to her death over three traumatic days."
Maher added that it is often a "true test of a community" as to how it looks after its most vulnerable.
"My mum did not deserve to die in hospital like that and my family deserve the right to know the causes and circumstances surrounding her death, as would any family who has lost a loved one."
Maher said she had attended a meeting at Middlemore Hospital on January 4, 2013, with her brother, chief medical officer Gloria Johnson, and Dr Catherine Simpson.
"At the meeting Dr Simpson stated 'that Mum would have had to been injected with a shipload of insulin to have recorded such low blood sugar levels'."