[1][2][3] Tall, pock-marked and having a pink complexion,[4] Mam Nai impressed both Nate Thayer and François Bizot as the most frightening Khmer Rouge individual they ever beheld.
[6] Together with Tang Sin Hean (Comrade Pon) Mam Nai helped Duch to perfect his interrogation techniques in order to purge perceived "enemies of the revolution" from the Khmer Rouge ranks.
By 1978, as the party paranoia of seeking unchallenged authority and the ensuing purges increased towards the end of Pol Pot's rule, more and more people were brought to Tuol Sleng.
[8] Mam Nai left the Khmer Rouge shortly before Pol Pot ordered Son Sen's assassination in 1997, living as a private small-scale farmer in the west of the country.
[10] At the trial he was asked questions regarding his involvement in the torture and murder of Phung Ton, former dean of Phnom Penh University, but Mam Nai carefully avoided incriminating himself.