Olympian Rob Hamill's quest for justice for a brother murdered by the Khmer Rouge has drawn an emotional response at film-festival screenings in London and New York.
The powerful documentary Brother Number One, which follows Mr Hamill to Cambodia in search of answers over the death of his older brother Kerry in 1978, has been screening at the Human Rights Watch international film festival.
Mr Hamill, who today will present a final screening in New York before flying home, said he had been overwhelmed by the response from the hundreds of people who had viewed the film.
"The response has been very emotional and it's been amazing. It really is compelling," he said.
"You can feel it in the audience and often they're left angry, and demanding to know how as a species we could have allowed this to happen to one another."
Kerry Hamill, with Englishman John Dewhirst, was tortured for two months at the Khmer Rouge prison Tuol Sleng (S21) after they were captured during a yachting trip.
Canadian Stuart Glass was shot dead when they were seized.
After signing confessions taken under duress that "admitted" their supposed CIA affiliations, they were executed on the orders of Khmer Rouge jailer Comrade Duch.
They are among 1.7 million people the regime is estimated to have murdered between 1975 and 1979.
Duch, whom Rob Hamill emotionally confronted in court, was found guilty of crimes against humanity, torture and murder and sentenced in July 2010 to 35 years' jail.
In February, the sentence was extended to life without parole and with no chance of appeal.
Mr Hamill said that Brother Number One - the name the Khmer Rouge's genocidal leader, Pol Pot, gave himself - was now being used to gather more victims for further court action.
"This has helped get victims to do what I did basically, and signing them up to be a civil party.
"There's really strong resistance from the Cambodian Government to continue with any further trials but through this film and though an organisation I met with yesterday, there's the potential to ratchet up the pressure a bit. It's created an emotional response and I believe that through an emotional response you get awareness and you get action."
The film, directed by multiple award winner Annie Goldson, had also been praised for showing the genocide from a Western perspective.
"I had some Cambodians come up to me after the last screening who told me, 'Thank you so much for doing this', and said it had put a fresh angle on the whole thing," said Mr Hamill, who rowed for NZ at the 1996 Atlanta Olympics and, with Phil Stubbs, won the inaugural Atlantic Ocean rowing race the following year.
The film has already featured in New York - at the renowned Tribeca festival - as well as others in London, Copenhagen, Gothenburg, Paris and Melbourne.
But Mr Hamill said its opening in Auckland last year was the most fulfilling.
"Nothing could beat that. It was really a tribute to my family. It was a good thing as I've discovered along the way that burying the hatchet just doesn't help.
"We as a family didn't talk about it for 30 years and I think the film has progressed a lot of things for our family, and hopefully for a lot of others who have been affected."
TV3 is to screen Brother Number One next month.By Jamie Morton @Jamienzherald Email Jamie