"Does a leopard change its spots? It's an interesting question," says Dr Paul Wood, 37, in his downtown Auckland apartment. He is lean, muscular, close-shaven, tattooed, eloquent and a coach in personal transformation.
Wood, who served 11 years of a life sentence for murder, runs Switch Consulting. He is his own best advertisement. His life was transformed through education. He was 18 when he went to jail, 35 when he graduated with a PhD in psychology after completing bachelor and master degrees in prison.
That David Bain chose a former cellmate as a groomsman made national news. Nancy Schroder, the mother of his victim, said she felt "bloody sick" he was out celebrating while her family still grieve.
The groomsman, Paul Russell Wilson, met Bain when both men were imprisoned together. Wilson was granted parole in December 2012 after serving 15 years' jail for the rape and murder of his 21-year-old girlfriend, Kimberley Schroder, 20 years ago.
The Parole Board described Wilson's behaviour in prison before releasing him as "exemplary and faultless".
Families of victims have every right to feel that way, says Wood, who does not know Wilson or Bain.
"The question for society is at what point do we give people the opportunity to demonstrate their regret and their desire to live a better life by allowing them the opportunity to move past that bad behaviour?
"The difficulty is by continuing to focus on that period - that was so long ago for people that were in a similar situation to me - is we make it harder for it to be a chapter rather than a defining part of that person's life."
Wood says it is the right of those he victimised to be unhappy that he enjoys freedom and had the opportunity for change that his actions took from his victim.
"The only thing you can trust is my behaviour. What I say isn't really relevant, words are cheap. I have done such harm to people there is no way I can alleviate that. How I live my life today is an indication of the regret I have."
As a youth, Wood was addicted to drugs, violent, immature and emotionally unable to cope with his mother's cancer. Three days after his mother died, Wood killed his 42-year-old drug supplier. "He had an aggressive interest in sex acts with young guys and I was someone who was ready to go off, someone who was ready to fight," he says. "He ended up being the focus of everything that led up to that."
As for the leopard's spots, Wood says elements of his nature are the same, such as a desire for social recognition and to give his best. "The difference is now these things are focused in a positive direction."
Once a crim always a crim, is a notion debunked by the discovery that the brain changes not just functionally but physically throughout life as a response to experience. Referred to as brain plasticity or neuroplasticity, modern research disproved the earlier assumption the brain's structure was set by early adulthood. Everyone is shaped by their habits and beliefs - hence Wood calls the personal development programme he offers "What's Your Prison" - but science confirms change is possible.
Wood can testify that it is a tough, ongoing process. Embedding change takes regular repetition, just, he says, as a farmer driving across a paddock at first leaves a faint impression. With repetition a pathway becomes so pronounced the farmer can take his hands off the steering wheel and the wheels will roll along the ruts.
There is always a conflict between punishment and rehabilitation. Wood says comment that prisons are too comfortable miss the point. It's not the physical environment that makes prison difficult, it's the company. "Imagine all the worst bullies you came across at school," he says. "Now you are in with all of those people, but there's no home time, it's 24/7. That's what prison is like."
Though prison generally impedes rehabilitation, Wood says there has been progress. After time in a rehabilitation programme, prisoners would be returned to the mainstream culture, a practice he describes as "polishing a piglet and then returning it to the pigsty". Some prisons now have specialist units for inmates to go to after completing programmes so they are not "recontaminated".
A stint of continued drug use early in his sentence resulted in Wood spending 10 months in Paremoremo prison's maximum security unit. "When I came out I had been heavily influenced by the values and culture of maxi." To successfully reintegrate, prisoners have to get past those prison cultures. When he speaks in prisons now, Wood tells inmates to expect it to take a month for each year in prison to adjust once released. Even with the benefit of bachelor and master degrees earned during a decade in prison, he says it still took him about a year to feel reasonably comfortable with freedom.
A significant increase in spending on prison rehabilitation is not a public or political priority and Wood understands the desire for retribution but says society has to ask what outcomes it wants. "If it is purely retribution and we don't care about the likelihood of people reoffending, then just increase punishment. If, on the other hand, we want to reduce people's likelihood of reoffending then we need to initiate programmes that have evidence indicates achieves that."
That he reformed without extensive programmes he puts down to the unusual help he got - such as from his PhD supervisors who went to Rimutaka Prison to cover work that had to be done in person. "You can have the best will in the world but if you aren't given the opportunities then [success] is going to be very limited."
Wood says he was aware of education possibilities because he had tertiary-educated relatives. "You can't expect people who haven't been exposed to that to be aware of it as an option."
Not that Wood expected it to lead to salvation. "When I started, my intention was to do a couple of psychology papers to understand what makes people tick in a very dangerous environment. I had no idea I'd be capable of a degree."