Corrections has been referred to the Director of Proceedings for falling to provide adequate care to inmate Vicki Letele who eventually died of advanced gastric cancer.
Deputy Health and Disability Commissioner Kevin Allan made the referral, the most severe recommendation he could make, in a report released today.
The report didn't identify the victim by name, but Letele's brother, David Letele, confirmed to the Herald she was the subject of the report.
The family did not want to comment further at this stage.
Department of Corrections national commissioner Rachel Leota said they have formally apologised in writing to the family and would like to apologise publicly.
"We fully accept the Deputy Health and Disability Commissioner's findings that we failed in our responsibility to ensure that this patient received health services of an appropriate standard, and breached the code of Health and Disability Services Consumers Rights," Leota said.
"On behalf of Corrections, I am sorry that we failed to deliver the appropriate standard of health services, which resulted in this woman's unnecessary discomfort and distress.
"We have been in touch with the patient's family with a view to meeting with them face to face to apologise for the distress caused to them."
In 2016 Letele was sent to the Auckland Region Women's Corrections Facility, in Wiri, for 10 offences of mortgage fraud that netted $500,000.
On her arrival she told staff she had been diagnosed with irritable bowel syndrome some months before.
Four months later Letele reported a burning throat and sore right ear, that she was unable to hold down food and that she was very light-headed and feeling weak. She also told a nurse who saw her that sometimes she woke up with acid in her mouth.
This information was relayed to the prison's medical officer who prescribed reflux drug, Losec.
A couple of weeks later the doctor, who still had not seen the patient, prescribed Letele Mylanta for heartburn and increased her dose of Losec.
Another couple of weeks on, the doctor finally saw Letele. He prescribed ranitidine, which decreases stomach acid production.
Letele continued to report reflux symptoms and three weeks after seeing the doctor arrived at a walk-in clinic held by the nurse. She was given different medication but returned to the clinic a couple of days later.
She was seen by a different doctor who suspected an inner-ear disorder and gave her medication to treat the nausea.
The next day she told a nurse she was vomiting frequently and the vomit contained black matter. She was scheduled for a review by nurses the next day.
By that stage she was in a wheelchair and described her pain as "10/10". Her oxygen saturation level was low, and her temperature was low.
She was sent to the emergency department at a public hospital where she was diagnosed with advanced gastric cancer causing near complete obstruction of the outlet to her stomach.
The Parole Board originally refused to release Letele on compassionate grounds, but a campaign that began on Facebook quickly gathered steam.
The Prime Minister at the time, Sir John Key, weighed in, and 12,0000 people signed a petition calling for her release.
A second application was successful in November, with the Parole Board stating she was "seriously ill and is unlikely to recover". She was expected to live for less than five months.
Letele died the following May.
She was survived by her partner Leah and their three children.
The deputy commissioner was critical of the initial doctor's lack of contact with the woman when prescribing medication, or increasing doses.
But he found the second doctor breached the code by failing to take into account her history or perform an appropriate examination.
Allan said the nurse's response to reports of black vomit was seriously deficient and lacked the required urgency.
He said Corrections failed in its responsibility to ensure she received services of an appropriate standard.
Allan recommended the doctor, nurse and the Department of Corrections all apologise to Letele's family and referred Corrections to the Director of Proceedings for a further review.
In response, Corrections provided evidence of staff training and hired an independent nursing educator to provide nursing staff with education on commonly presenting health conditions. Corrections also commissioned an independent review.