The alarm was raised after tests carried out a few minutes later revealed his heart was beating faster than normal.
His condition rapidly deteriorated before he died at 3pm, the cause of death attributed to congestive heart failure and stroke.
Ms Butler's mother, who went straight to the hospital after receiving a phone call on the golf course that Mr Butler might not make it through the night, arrived half an hour too late.
She was left feeling exhausted and lost, her daughter said, after being met not by Mr Butler's doctor, but by nursing staff who gave her the cause of death and commented how "chirpy" he had been the day before.
His shoes were missing when she was shown to his room and handed his belongings, which included a half-eaten sandwich.
Ms Butler said the family were not made aware of their right to request an autopsy and at that time also did not know a "not for resuscitation" (NFR) form had been filled out by hospital staff.
Appalled and left with unanswered questions, Ms Butler began her own investigation into her father's care soon after his death.
She now suspects his death emanated from a cyst on his brain stem, which she says was detected in a CT scan in July 2005 and claims it was "misread" by a Waikato Hospital consultant in a discharge summary later that month and not noted in later entries in his medical file.
She said this had left her to question whether her father could have lived longer had symptoms over the last six years of his life had been linked to the cyst and investigated further.
Her inquiries have also revealed how forms had not been properly filled out by staff - and was horrified to discover a patient-initiated not for resuscitation authorisation form had been completed without her father's signature.
The health board has since admitted the form was signed not by Mr Butler, but by the hospital cardiology registrar - and that the correct form should have been a "medically initiated" resuscitation form.
Melody-Rose Mitchell, nurse manager of the hospital's cardiology, cardiothoracic and vascular surgery department, has written to Ms Butler explaining that that form should have been used.
The health board's policy states that in most circumstances, such forms are made in consultation with "the patient, the family and other health professionals involved in the care of the patient".
Ms Butler also discovered a raft of errors in her father's other documentation, including a nursing summary on June 14 not filled out until 3.30pm and without noting the time Mr Butler's condition was found to have deteriorated.
No dates were also recorded on several entries and two showed the wrong date.
But Ms Butler said she was more angry about how her mother was treated, describing it as "disgraceful".
"It's just very sad she didn't get to say goodbye but more important was the disempowerment of her role and the whole family's role during the process," she said.
"They came upon him unwell first thing in the morning but we weren't advised until late in the piece ..."
Last month, she lodged a complaint with the Health and Disability Commission and, if she is unsatisfied with their response, will take the case to the Human Rights Review Tribunal. "I'd like to see a sincere acknowledgment and I want it pretty thoroughly investigated, so others aren't placed in the same situation.
"It's been painstaking having to investigate all of his medical records myself - but in my personal view, I'd encourage people to take the initiative themselves, get the notes, get themselves empowered and be their own auditor, just as a matter of course."
Ms Mitchell has told her that noting the time of her father's deterioration should have been a "minimum standard".
She could not explain why family members had not been able to speak to Mr Butler's doctor, and apologised for a "poor standard of documentation" and a "lack of appropriate communication and compassion".
The hospital has now introduced a new auditing regime ensuring forms are checked by charge nurse managers.
Mr Butler's cardiologist, Dr Chris Nunn, said he had met the family but as the matter was now before the commissioner, he could not comment further.
"We will fully co-operate with his office during the investigation.
"We appreciate this as being a really difficult time for Mr Butler's family and reiterate what we said [that] we are deeply sorry for the poor standard of documentation in this case."