Nuon Chea, with real name Long Bunruot, was born in 1927, in Battambang.
He completed his secondary studies in Bangkok, Thailand where he lived until 1948. He then studied law in Bangkok but did not complete his studies.
Between 1945 and 1948, he was part-time public servant at the Ministry of Foreign Affairs and joined the Thai Communist Party (TCP).
In Cambodia in 1948, he joined the Indochinese Communist Party (an independent Vietnamese movement led from Vietnam by Hô Chi Minh). In 1951, he took part in the creation of the Revolutionary Party of the Kampuchea People (RPKP), and in the transformation of this party into the Kampuchea Communist Party (KCP). In 1962, he was appointed Deputy Secretary General of the KCP.
Between 1970 and 1975, Nuon Chea was the vice president of the High Military Commandment of the People’s Armed Forced for the National Liberation of Kampuchea. (PAFNLK), as well as the head of the political leadership of the army (during the Vietnam War).
On 17 April 1975, Phnom Penh fell to the Khmer Rouge who then took the control of the rest of the country.
On 9 October 1975, Nuon Chea was designated 'Brother Number 2' of the Permanent Committee of the Central Committee, in charge of labour, social welfare, culture, propaganda and formal education (or Conscience work).
From 25 September until 15 October 1976, he was acting as Prime Minister of the Democratic Kampuchea. Between 1976 and 1979, he was President of the Assembly of the Democratic Kampuchea.
As head of the security of the regime, Nuon Chea was considered the chief ideologist of the Khmer Rouge and as a key actor of the revolution. He was the most powerful man after Pol Pot, and when the latter died, Chea became the party’s highest ranking person.
The Khmer Rouge "revolution" is said to have lead to the death of 1,7 millions deaths before the Vietnamese troops overthrew the regime in 1979.
On 19 September 2007, the Extraordinary Chambers of the Courts of Cambodia issued an order of provisional detention for Nuon Chea, in which he was charged with crimes against humanity and war crimes. He was arrested the same day by special units of the army and police at his home in the jungle close to the Thai border, where he was living since an agreement had been reached in December 1998 with the Cambodian government. He was brought into the custody of the ECCC.