Son was born in 1920 in Trà Vinh Province (present-day Vietnam) during the French colonial period[1] to a Khmer Krom father and a Vietnamese mother.

[3] During the First Indochina War, he was recruited by Vietnamese communists (Viet Minh) to serve as President of a newly formed Cambodian People's Liberation Committee (CPLC) in Battambang.

His nom de guerre was intended to capitalise on the popularity of Sihanouk's banished rival, Son Ngoc Thanh, then still languishing in exile in France.

Son remained a senior figure in the Party, albeit largely operating from Hanoi in North Vietnam until 1972, when at the request of Ieng Sary, he was sent to hospital in Beijing to be treated for high blood pressure.

[5] His death further lessened the influence of the Hanoi-trained communists on the Khmer Rouge, correspondingly increasing the power of the hardline Party 'Centre' led by Pol Pot.