A notorious Khmer Rouge leader returned to the prison where he oversaw the torture and murders of tens of thousands of Cambodians in the 1970s.

Kaing Guek Eav, also known as Duch, led judges with a United Nations-backed tribunal on a tour of the infamous Tuol Sleng prison Wednesday in the capital of Phnom Penh. The 65-year-old jailer is expected to describe how he directed the gruesome operations at the former school.

An estimated 14,000 Cambodian men, women and children were imprisoned, tortured and killed at Tuol Sleng, also known as S-21. Only a few people are believed to have survived the ordeal.

Duch broke down in tears Tuesday as he led tribunal officials on a tour of the Cheoun Ek execution site outside Phnom Penh.

He is one of five former Khmer Rouge officials to be charged with crimes against humanity during the regime's four-year rule, which ended in 1979.

Nearly two million people died of overwork, starvation and disease as the Khmer Rouge emptied the cities and forced millions of Cambodians into agricultural cooperatives.

Some information for this report was provided by AFP, AP and Reuters.