North Korea prison camps fill up amid crackdown on attempted defectors SEOUL, South KoreaNorth Korea's prison population has swelled in recent years with those caught fleeing the country under a crackdown on defections by young leader Kim Jong Un, according to defectors living in South Korea and researchers who study Pyongyang's notorious network of labor camps and detention centers. Soon after he succeeded his father as North Korean leader, Kim is believed to have tightened security on the country's borders and pressured Pyongyang's neighbor and main ally, China, to repatriate anyone caught on its side of the frontier. In interviews with The Associated Press and accounts collected by human rights groups, North Koreans who have managed to leave the country say those who are caught are sent to brutal facilities where they now number in the thousands. "They are tightening the noose," said Insung Kim, a researcher from the Database Center for North Korean Human Rights who gets to interview most defectors soon after their arrival in South Korea. This is to set an example to the North Korean people. North Korean prisoner escaped after 23 brutal years A girl is beaten to death for hiding food The choice: Take a beating or miss a meal In an effort to reveal what North Korea's leader does not want the world to see, "60 Minutes" interviewed a prison escapee from a modern-day concentration camp -- one of the secret prisons hidden in the mountains, 50 miles from North Korea's capital, Pyongyang. The institution is called Camp 14, and according to human rights groups, it's part of the largest network of political prisons in the world today. Some 150,000 people are believed to be doing hard labor on the brink of starvation in these hidden gulags. But it's not just those who have been accused of political crimes, it's their entire families -- grandparents, parents, and children -- a practice called "three generations of punishment." Very little was known about Camp 14 until a young man showed up in South Korea with an extraordinary tale to tell. His name is Shin Dong-hyuk and, as "60 Minutes" first reported in December, he said he had not only escaped from Camp 14, but he was born there. He's believed to be the only person born and raised in the camps who's ever escaped, and lived to tell about it. Who is Kim Jong Un? The plight of those caught fleeing the North was highlighted last month when nine young North Koreans were detained in Laos, a key stop along a clandestine escape route through Southeast Asia that had previously been thought safe. Instead, the Lao government turned them over to Pyongyang. While the high-profile nature of their repatriation might offer them some protection, human rights group fear for them. "Forced repatriation from China is a pathway to pain, suffering, and violence," according to "Hidden Gulags," an exhaustive 2012 study on the prison camps by veteran human rights researcher and author David Hawk. Arbitrary detention, torture and forced labor are inflicted upon many repatriated North Koreans. In 2003, Park Seong-hyeok, then 7, and his parents were arrested trying to reach Mongolia from China and sent back to North Korea. He ended up at a prison in the northern city of Chongjin, where he was packed in with other kids, some of them homeless children rounded up off the streets. They were blindfolded each day and forced to clear land for agriculture, he said. If they refused, they were beaten. "I couldn't even tell whether I was alive," Park said. We were provided five pieces of potato a day, each about the size of a fingernail. After a few months, he managed to escape after his uncle bribed the guards. With the help of relatives, he made it to South Korea, where he now attends a special school for North Korean defectors. But he assumes his parents, who he has not seen in 10 years, remain imprisoned in the North. In the 18 months since Kim took power, any hopes the 20-something ruler would usher in a new era of human rights reforms have been squelched. Defectors pose a particular threat to the Pyongyang regime, human rights groups say, because of the stories they tell the world about the plight of the North Korean people, and the information and money they send back in. North Korea considers those who leave the country to be guilty of treason and subject to up to five years of manual labor. In addition, the penal code states if the nature of the defection is "serious" - taken by most researchers to mean if the defector gets the help of South Korean or American Christian missionary groups as opposed to trying to reach China for work purposes - the defector risks an additional charge of anti-state activities that could mean life in prison or even death. North Koreans considered hostile to the government can spend the rest of their lives, along with their families, in one of at least five sprawling labor camps or colonies that encompass fields, factories, mines and housing blocks. Modeled on the Soviet Gulag system, the areas are chosen for their natural barriers, such as mountains and rivers, their remoteness, and their access to natural resources like wood and coal, according to human rights groups. Defectors may end up in those camps, but are typically held first in other detention facilities close to the border, just as brutal but more resembling traditional penitentiaries, according to human rights groups. Still, at least one labor camp, Yodok, now has a special section for those repatriated from China that houses thousands of inmates, according to Kang Cheol-hwan, a former inmate there.