Chris Marnewick was exposed to the death penalty at a very early age. It burrowed into his consciousness and has never fully left him.
He was 8 when an 18-year-old girl disappeared in Pinetown, a satellite town just west of Durban, South Africa. Joy Aken's body was found a week later in a culvert 100km from where she was taken.
Her killer, Clarence van Buuren, was eventually caught, found guilty of murder and executed by hanging on June 10, 1957, after a murder trial that captivated the nation.
Marnewick, sitting in his study in East Auckland almost 59 years later, vividly recalls the case that he followed closely in the newspapers at the time, reading each story over his dad's shoulder.
"Just before he was executed, my dad and I drove through Pretoria and my dad, with the wave of a hand, said, 'That is the place where they are going to hang Van Buuren'."
He was pointing to Pretoria Central Prison, the official site of capital punishment in South Africa from 1931, which gained particular notoriety during the apartheid era.
The prison, and the maximum security annex built behind it, became the setting of his debut novel, Shepherds and Butchers.
Written in Auckland and published by Umuzi in South Africa in 2008, the book picked up a collection of national literary awards and nominations, including being shortlisted for the Commonwealth Writers' Prize in 2009 in the Best First Book Award: Africa category.
The film rights were bought a year later by the same production company behind the 2013 film Mandela: Long Walk to Freedom and the movie, starring Brit actors Steve Coogan and Andrea Riseborough, premiered to positive reviews at the Berlin Film Festival this month.
But far from the glitz and glamour of the festival circuit, Marnewick sits in his Bucklands Beach home worrying the central theme has been lost in translation.
He hasn't seen the film and is not sure he will.
"I still have the worry, and I'll confess that openly, that they're going to lose the real message.
"The theme is that killing is wrong, killing human beings is wrong. That's my theme and, alongside it, that making people kill on our behalf is wrong because the killing of a human being changes the killer."
Marnewick was in regular contact with screenwriter Brian Cox and, after seeing the script, convinced Cox to correct factual inaccuracies.
But he couldn't persuade him to change the storyline the film-makers were pursuing.
Marnewick says he understands it is their movie and not his.
"I am happy with that because that absolves me from all blame and criticism."
The book, Marnewick says, is about life and death and what it means to take someone's life. It is set in apartheid-era South Africa but that is only the backdrop.
Some reviews suggest the life and death issues are a dual theme with that of apartheid.
"It's not an apartheid story, although they are now making a movie as if it is," says Marnewick.
About 4000 people were executed in the century leading up to South Africa's final hanging in November, 1989. Most were black Africans and other people of "colour".
Marnewick poured his own experiences into the book's main character, barrister Johann Weber - renamed John Weber for the film.
In 1963, a classmate of Marnewick's was murdered and his killer executed. Marnewick was 15. He went on to qualify as a High Court barrister and then became an acting High Court judge, sometimes defending and sometimes sentencing people accused of appalling crimes.
In 1987, 164 people were executed in South Africa, the highest annual toll in the country's history.
"And I started wondering about what that would do," Marnewick says.
"How killing on that scale would affect the people who were doing the killing on behalf of the state.
"I know the trauma that a lawyer goes through defending someone for his life - where you stand on your feet in court, cross-examining the witness, and a wrong question can see your client being taken away and hanged.
"That's the pressure, that's the stress. And of course it tells."
Marnewick defended between 40 and 60 murder cases. The exact number is a blur but he proudly remembers the overall result.
"None of my clients got the death penalty."
One case stands out.
The successful acquittal of Xerxes Nursingh led to death threats and, ultimately, Marnewick and his family left South Africa for New Zealand.
"This was almost like the case in the book, one of those hopeless cases where a young student, 18 years old, had shot and killed his mother and his grandparents."
A former law student of Marnewick's asked him to take on the case.
"She said to me: 'My best friend has been killed by her own son and he needs a lawyer'."
Marnewick defended Nursingh on the triple murder charge and won what was a high-profile trial in the Durban High Court in 1994. He ran the same defence he would later use in Shepherds and Butchers - temporary insanity, or sane automatism.
The defence was founded on the premise that Nursingh's mother had abused him emotionally and sexually.
In 1999, Marnewick and his family moved to New Zealand permanently. In 2002, he started work on Shepherds and Butchers.
He dug up case files of the 21 people executed in just three days in December, 1987 and found that 32 people died in five days of hanging. A young prison warder named Johan started working at Pretoria Central Prison and Maximum Security in 1986, aged 18. He was present for all 32 executions.
Marnewick interviewed Johan, whose job it was to guard prisoners sentenced to death - to feed them, take them for haircuts, sit with them when they had visitors.
He was the shepherd.
But on the day of the execution, he became the butcher. From 6am, Johan would escort a prisoner during the last hour of his or her life.
He would take them to get their fingerprints recorded, sit next to them during a chapel service, and stay with them when the clock struck 7am. He watched as they took their final breath.
"And then when they had finished the execution - he didn't do that, that was the hangman's job - he had to go downstairs, take the bodies off the rope, go for another service with the deceased's family then go and bury the bodies and register their deaths," Marnewick says.
What was unique and "utterly unthinkable" about this system, was that the warders were on first-name terms with the people they were helping execute.
They were both shepherds and butchers and, as Marnewick believed, the role exacted a terrible toll.
"They became traumatised and, eventually, Johan told me, addicted to the process of killing those prisoners, although they weren't physically doing the killings."
Johan told Marnewick it became an adrenaline rush that he and others began to look forward to.
Marnewick says some warders took their own lives and alcohol abuse was rife.
There were brushes with the law, bar fights, road rage incidents.
It's clear now they were suffering post-traumatic stress, Marnewick says. After witnessing other people suffer at such a scale, they started suffering themselves.
Shepherds and Butchers follows the fictional story of a young prison warder named Leon Labuschagne, who at 19 and after a two-week stint of 32 executions, loses control and kills seven men.
He faces the death penalty and barrister Johann Weber defends him using the temporary insanity defence and, in doing so, investigates the life of those working on Death Row and the effects that the killing has on them.
The novel also includes snippets from the true story behind the execution that started it all for Marnewick, that of Clarence van Buuren.
Though capital punishment has dominated his life, he wanted to shine a light rather than dictate.
"It's got to be wrong in principle to take away life.
"But when it comes to the book, I didn't want my views to influence the reader. I wanted the reader to see the abhorrent crimes that the 32 men had committed and were hanged for.
"And then see at the same time the abhorrent methodology and process adopted in killing those very same people."
Shepherds and Butchers will be republished this year to coincide with the film and is due in bookstores here in the next couple of months.
Whether the movie will be released here depends on its festival circuit performance.
For Marnewick, in many ways, it doesn't matter. He says he has finally moved on from the subject of the death penalty.
He has written three other novels since his debut, writes fulltime, attends literary festivals, teaches a creative writing course at a local library, and spends time with his wife Ansie and sons Michel and Jacques and their own growing families.
But that case that burrowed into his consciousness when he was a little boy is hard to silence.
"Humans have an inhibition against killing other humans and [it leaves] a severe psychological impact. History has to be recorded by the people who lived through it."