Between 150,000 and 200,000 North Koreans live in prison camps surrounded by electrified fencing, according to South Korean government estimates and Human Rights Watch. The worst camps are for those who commit political crimes, and offenders can have their entire extended family imprisoned with them. As many as 40% of camp prisoners die from malnutrition while doing mining, logging and agricultural work with rudimentary tools in harsh conditions, according to a 2011 Amnesty International report.