The same year he was offered a place in the prestigious Lycée Sisowath in Phnom Penh where he completed his Baccalaureate in mathematics, scoring second in the entire country.

[12] The institute was a cradle of activism under the directorship of Son Sen who was later to emerge as the Defence Minister of the Khmer Rouge and Duch's immediate superior.

On 28 August 1966, Kek Iew received his teaching certificate and was posted to a lycée in Skoun, a small town in Kampong Cham Province.

Following the arrest of three of his students, he fled to the Khmer Rouge base in Chamkar Leu District where he was accepted as a full member of the Communist Party of Kampuchea.

A few months later, he was arrested and witnessed others being tortured at the Prey Sar prison[14] by Norodom Sihanouk's police for engaging in communist activities.

In 1970, when he was released following the amnesty granted to political prisoners by Lon Nol, he joined the Khmer Rouge rebels in the Cardamom Mountains bordering Thailand.

Communist groups in France's former colonies in Indochina borrowed the French World War II expression 'maquis' when referring to their resistance movements in the jungles.

[15] In the zone under the control of the Khmer Rouge, Kek Iew took on his nom de guerre Comrade Duch (IPA:[dujc]) and became a prison commandant.

[12] The Tuol Sleng prison camp was initially headed by In Lon (aka Comrade Nath) with Duch acting as deputy.

[25] As the party purges increased toward the end of the Democratic Kampuchea period, more people were brought to Duch, including former colleagues, among them his predecessor at Tuol Sleng, In Lon.

Shortly after the Paris agreement in October 1991, he moved with his family to the small isolated village of Phkoam close to the Thai border.

Shortly after his wife's murder, Duch began attending the prayer meetings of the Golden West Cambodian Christian Church held in Battambang by Christopher LaPel, an evangelical Khmer-American.

When fighting broke out in 1996 following the split of the Khmer Rouge and the coup to oust Prince Rannariddh in 1997, he fled with his family to the Ban Ma Muang camp just inside Thailand.

He settled in the village of Andao Hep in Rattanak Mondul and worked closely with World Vision International, the Christian relief agency.

Duch was prosecuted by international co-prosecutors William Smith and Anees Ahmed and was charged with "personally overseeing the systematic torture of more than 15,000 prisoners.

[5] On 6 April, he told the tribunal that "Mr Richard Nixon and [Henry] Kissinger allowed the Khmer Rouge to grasp golden opportunities" following the American bombing of Cambodia.

[7] In his final statement before the tribunal he acknowledged his involvement in Khmer Rouge-era crimes, including the execution of more than 12,000 Tuol Sleng prisoners, but said they were committed by a "criminal party".

His Cambodian lawyer, Kar Savuth demanded his client's acquittal and release, while his international counterpart, François Roux pressed judges to hand down a lenient sentence.

[38] On 26 July 2010, Duch was found guilty of crimes against humanity, torture, and murder; he was sentenced to 35 years imprisonment, with a pre-trial detention credit of 11 years being applied to his sentence and an additional controversial five-year deduction because his period of pre-trial detention exceeded the maximum allowed under Cambodian law.

[42][43][44] After serving ten years in prison, on 2 September 2020, Duch died at the age of 77 at the Khmer–Soviet Friendship Hospital of chronic obstructive pulmonary disease.