
S-21 (stands for Security Office 21) was originally a high school since 1962. In May 1976, when the Khmer Rouge was in power, it was converted into Angkar’s premier security institution, specifically designed for the interrogation and extermination of anti-Angkar elements (Angkar means commander). There were many similar prisons located at other parts of of Phnom Penh at that time.


All the classrooms of this former high school were converted into prison cells. Windows were enclosed by iron bars and covered with tangled barbed wire to prevent possible escape by prisoners.

The classrooms on the ground floor were divided into small cells, 0.8 x 2 meters each, designed for single prisoners.

From the picture above, you can see the bed frame and some iron bars on it. The iron bars were used to shackle one or both legs of each prisoner. By doing so, the Khmer Rouge could ensure that their prisoners were unable to make any escape.


The rooms on the top floors of all four buildings (as seen above), each measuring 8 x 6 meters, were used as mass prison cells. On the middle floors of these buildings, cells were built to hold female prisoners.

There were a lot of workers in the S-21 complex, totalling a number of 1,720. These workers are categorised into four main units: Internal workforce, Office personnel, Interrogation unites and General workers. Most of the "general workers" were under confinement.
Within each unit, there were several sub-units composed of male and female children ranging from 10 to 15 years of age. These young children were trained and selected by the KR regime to work as guards. Most of them started out as normal before growing increasingly evil. They were exceptionally cruel and disrespectful toward the presoners and their elders.

The above picture shows iron bars of different lengths used to mass-shackle the prisoners. The short iron bar was about 0.8 meters up to 1 meter long, and was designed for 4 prisoners. The longer one was 6 meters, and held 20 to 30 prisoners. Prisoners were fixed to the iron bar on alternating sides, so they had to sleep with their heads in opposite directions.
Every morning at 4:30am, all prisoners were told to remove their shorts, down to the ankles, for inspection by prison staff. Then they were told to do some physical exercise just by moving their hands and legs up and down for half an hour, even though their legs remained restrained by iron bars.
The prisoners had to defecate into small iron buckets and urinate into small plastic buckets kept in their cells. They were required to ask for permission from the prison guards in advance of relieving themselves; otherwise they would be beaten or receive 20 to 60 strokes with a whip as punishment. In each cell, the regulations were posted on small pieces of black board. The regulations read as follows:
1. You must answer accordingly to my questions. Do not turn them away.
2. Do not try to hide the facts by making pretexts of this and that. You are strictly prohibited to contest me.
3. Do not be a fool for you are a chap who dares to thwart the revolution.
4. You must immediately answer my questions without wasting time to reflect.
5. Do not tell me either about your immoralities or the revolution.
6. While getting lashes or electrification you must not cry at all.
7. Do nothing. Sit still and wait for my orders. If there is no order, keep quiet. When I ask you to do something, you must do it right away without protesting.
8. Do not make pretexts about Kampuchea Krom in order to hide your jaw of traitor.
9. If you do not follow all the above rules, you shall get many lashes of electric wire.
10. If you disobey any point of my regulations you shall get either ten lashes or five shocks of electric discharge.
Because of such regulations, the inmates were frequently severely beaten. Bathing was irregular, allowed only once every two or three days, and sometimes once a fortnight. Unhygienic living conditions caused the prisoners to become infected with diseases like skin rashes and various other diseases. There was no medicine for treatment.

In the wake of its renovation following the fall of the Khmer Rouge regime, Tuol Sleng, the historical museum of genocide under the Khmer Rouge regime, opened in 1980 and welcomes the public to come and visit. About 50 people visit the museum on an average day. Once they come to the Kingdom of Cambodia, tourists seldom miss visiting this horrifying educational site.

Above picture shows the mug shots of the little children being held prisoners at S-21.

The above pictures are just few of the many mug shots of the genocide victims taken during the Khmer Rouge regime. Other pictures on display (like the one below) show evidence of the brutality the Khmer Rouge used to torture and exterminate their prisoners.

Yet another collection of skulls of the victims in S-21.
Tuol Sleng Genocide Museum hopes to preserve "S-21" as a reminder not only of Cambodia’s recent history but of the inhumanity that sometimes overwhelms ordinary human beings.