The curse-lifting ritual that led to the death of Janet Moses has left Massey University cult researcher Heather Kavan mystified.
Dr Kavan, who has been researching cults since the 1990s, spent six weeks at the trial of the nine people accused of the manslaughter of 22-year-old Ms Moses.
She has analysed the attempted exorcism against previous academic research, and plans to write a paper on her findings.
In October 2007, Ms Moses died after her family attempted to lift a makutu, or curse, they believed she had been given as a result of the theft of a concrete lion from a Wairarapa pub.
But what began as prayers descended over about four days into a chaotic, improvised ceremony to drive demons from Ms Moses, who was believed to be possessed.
At a seminar at Massey University yesterday, Dr Kavan said that the family members' actions could not be rationalised easily.
Some of their behaviours could be explained by "group think"- when members of a highly cohesive group lose their moral judgement and make irrational decisions.
The group had little information on how to lift a makutu and lacked an impartial leader, but were still committed to the ritual.
They also believed there was a high threat to them from the makutu, and had isolated themselves from the outside world by pulling curtains and stationing guards outside the house, Dr Kavan said.
However, many of the symptoms of group think were not exhibited. The family were not confident that they were invulnerable, did not show self-censorship of ideas or interpret the silence of others as agreement.
But there was evidence of other "possession-trance experiences," seen in cults around the world, she said.
As the ceremony got more intense the moral judgment of the group declined, and everybody continued the ritual even though it was clearly failing.
During the exorcism, about 30 people held hands in a circle and chanted "go with peace and love", before pouring water into Ms Mose's eyes and mouth to cleanse her.
When she vomited, her clothes were put in the laundry, and to avoid them people urinated in a corner of the lounge. Temperatures rose to 40 degrees.
The floor was soaked with water, but instead of seeing this as a sign things were getting out of hand a family member cut a hole in the floor to let the water out, Dr Kavan said. On the day Ms Moses died, most had not slept for four days. The group were still fully convinced Ms Moses was possessed - when she struggled and yelled, they thought the demon was talking.
And hard as it was to believe, they were still motivated by their care for her, Dr Kavan said.
"They actually were trying to help."
At the end of the trial five family members were found guilty, one was discharged and three were acquitted by the jury.