Shin Dong-hyuk said his earliest memory of life in a North Korean prison camp was the public execution that inmates were forced to watch when he was five.
Inmates, he told a hushed audience in Seoul, were so hungry that they devoured live rats and the uncooked hooves of a goat that prison guards had thrown away after slaughtering the animal.
One seven-year-old girl was clubbed to death for stealing a few grains of wheat. Shin said he felt lucky when a warden ordered the tip of his finger chopped off, rather than having him executed, for damaging a piece of sewing equipment.
"We toiled as bid and ate what they gave us; we took their beating and starved when they didn't give us anything," said Shin, 31, who escaped in 2005. "We were expendables they were keeping as beasts of labour, to get the most out of us before we die."
Shin's account was dramatic but not particularly new; over the years, defectors from North Korea, including a handful of survivors of its prison camps like Shin, have told similar stories in interviews, at human rights conferences and in documentaries and memoirs. What made the accounts given by Shin and another defector from North Korea unusual was that they were addressing the first UN panel established to investigate allegations of human rights violations by the North Korean government.
The three-member panel was launched by the UN Human Rights Council in March with a one-year mandate to investigate what the council called allegations of "systematic, widespread and grave violations of human rights," including possible crimes against humanity.
The panel's work marks the international community's most direct challenge to North Koreas Kim Jong-un over his country's human rights record.
North Korea denies violating human rights and has rejected UN resolutions calling for better treatment of its people as a "political plot".
In a joint letter delivered to the panel, groups of North Korean defectors, including one called Free the NK Gulag, said they hoped the inquiry would lead to the indictment of "Kim Jong-un and his clique" in the International Criminal Court.