Lim Hye-jin described watching interned political dissenters set on fire, beheaded and shot dead en masse in collective punishment following escape attempts, in an interview with the Daily Mail.
The revelations come as tensions continue to boil on the Korean peninsula, stoked by the aggressive posturing of Donald Trump and senior members of his administration.
After being briefly imprisoned herself for illegal training, Ms Lim reportedly defected from the Democratic People’s Republic of Korea (DPRK) 15 years ago, and now lives in the southern capital, Seoul.
She said: “We were manipulated not to feel any sympathy for prisoners. We were told they had committed terrible crimes. Now I know they were normal people so I feel very guilty.
“I feel so betrayed by leaders who lied to us. We were told not to see these people as humans. Now I feel traumatised.”
In one incident, which Ms Lim described to the Daily Mail, a pair of brothers made a temporarily successful bid for freedom, and seven members of their family were executed on the spot in revenge.
The brothers were later dragged back to the camp, pelted with stones by prisoners forced to participate in the punishment, then beheaded. Ms Lim said this was done as “a warning” to the other inmates.
Ms Lim also reported seeing a woman stripped naked and set on fire, by guards who “do not see [prisoners] as human beings, just as animals”, and “affairs” between male prison guards and inmates which were “basically rape”.
There are an estimated 200,000 people in prison camps across the pariah state, and tens of thousands more in so-called “re-education” camps run along similarly brutal lines.
Tensions between the DPRK and the southern Republic of Korea, the US and other Western-allied nations such as Japan are higher than they have been for years.
US President Donald Trump has threatened Pyongyang with “major conflict” if it doesn’t halt its nuclear programme, while his Vice President Mike Pence made a surprise visit to the demilitarised zone bisecting the peninsula and warned “the era of strategic patience is over”.
A French amphibious assault carrier sailed into Japan's naval base of Sasebo on Saturday ahead of drills that risk upsetting China, which faces pressure from the United States to intervene and put a stop to the DPRK’s increasingly frequent ballistic missile tests.
Amid this geopolitical posturing, human rights have often been overlooked. One of the United States’ most experienced negotiators recently urged President Trump to lift sanctions and provide “humanitarian assistance” to North Korea, arguing that punitive measures and military aggression harm ordinary Koreans while leaving Kim Jong-un’s party elite unscathed.