Heather Ann Bills died from a massive insulin overdose, the chief coroner has ruled.
Ms Bills, 64, died in Middlemore Hospital in January, 2013, six weeks after being rescued from the flames of an explosive fire at her Orakei, Auckland, home.
Yet it was not her burns injuries that killed her.
Instead, a lengthy inquest into her death in September considered whether she was assisted to commit suicide.
Chief coroner Deborah Marshall released her findings into Ms Bills' death on Friday, concluding the cause of death was a "non-accidental overdose of insulin", which caused an irreversible brain injury.
Ms Bills was not diabetic and had not been prescribed insulin.
She was described by Ms Marshall as not accepting visitors or taking telephone calls in hospital.
"She was largely uncommunicative during her stay and often expressed a desire to die."
A police investigation undertaken after her death also concluded Ms Bills ended up in Middlemore Hospital in November because she planned to burn her house down before attempting suicide, but instead got caught in the explosion.
Police suspected three medical workers of administering the fatal dose to Ms Bills on the night of December 26, 2012.
In her findings, Ms Marshall said that expert witnesses testified that the "precise timing of the introduction of insulin is difficult to establish" due to a number of variables, including access to insulin and where and when nurses and other staff were present.
Name suppression orders of the workers with access to Ms Bills are in place.
The case remains open.