Tuol Sleng Genocide Museum – S21

Barbwire in the hallway to prevent prisoners from jumping to their death

Tuol Sleng Genocide Museum, known as S-21, is a very intimate and personal experience of man’s inhumanity to man. Located in downtown Phenom Penh, Cambodia, the museum walks visitors through the Cambodian Genocide.

Why should you visit?

It’s not pretty and it’s not fun. In general, touring Cambodia is delightful. However even though the Genocide Museum is difficult to stomach, it’s a lost opportunity if you skip the chance to learn about Cambodia’s history at the museum. So we highly recommend that you add the museum to your agenda.

We prepared for our visit by educating ourselves with a little Google research. Watching The Killing Fields is a good place to start. It’s ok to visit the museum without understanding everything about the Cambodian Genocide history. Yet, a little pre-education will lay the framework for a more productive visit.

Today, Tuol Sleng Genocide Museum seeks to allow the public to study the genocide and learn to become peace missionaries. 

Site History

High School: 1962 – 1975

  •  Preah Ponhea Yat High School was built in 1962.

Prison and interrogation center: May 1976 – January 1979

  • The Khmer Rouge regime converted the school into an interrogation and detention facility.
  • Named Security Prison 21, or S21, the facility houses prisoners. 

Tuol Sleng Genocide Museum: Late 1979 – present

  • The facility operates as a genocidal educational facility for those wishing to learn.

Backstory in Cambodia

Controlled by the Khmer Rouge, the Communist Party of Kampuchea came to power on April 17th, 1975. The Khmer Rouge sought to form a classless agrarian utopia. And many of its members were young, poorly educated men and boys from the countrysides.

So they shut down banks, abolished the national currency, and terminated private markets. The Khmer Route even confiscated private property.

This new government set a goal of cultivating approximately three tons of rice per 2.5 acres. That’s roughly double the average crop harvest, so it was a difficult goal to meet.

To make this happen, the Khmer Rouge attempted to create agricultural workers and laborers out of city dwellers. They forced over two million residents of Phnom Penh to march out of the city and into the countryside.

Forced evacuations/New York Times

Within a few days, the city of Phnom Penh, and the Preah Ponhea Yat High School, were empty.

S-21 Purpose

Enemies of the state (ykhbot cheat) are sent to S-21 for torture, confession, and execution. Many of Cambodia’s everyday-citizens became enemies of the state overnight. Some because of their educations. Some simply because they wore glasses.

Arrival at S-21

Prisoners arrived at S-21 blindfolded and unaware of their imminent execution. The Khmer Rouge had a systematic plan in place to dehumanize the prisoners and break their spirits. And separating families was the first step.

Prisoner rules on display at Tuol Sleng Genocide Museum in Phnom Penh.
Prisoner rules
  • Children
    • Separated from their parents and family
    • Sent to Choeung Elk (The Killing Fields)
    • Executed
      • “When children arrived at the center, I gave the order to kill them because we were afraid those children would take revenge.” Kaing Guek Eav, AKA Dutch 
  • Prisoner: Male and Female teens and adults
    • Photographed on entry
    • Height and weight measured
    • Surrendered clothing
    • Shackled to the floor in a small cell
    • Not allowed to speak
    • Not allowed to roll over on the floor
    • No eye contact
    • No bathing
    • Food is rarely provided
Mug shots from prisoners at Tuol Sleng Genocide Museum.
Incoming prisoner photographs

S-21 Torture

The interrogators needed confessions from the prisoners, one way or another. Failure to obtain a confession meant that the interrogator or guard may be enemies of the state who need execution. So interrogators tortured prisoners relentlessly.

To stop the torture the prisoner must confess to the following:

  1. Confess to all counterrevolutionary crimes
  2. Create a list of their associates called “strings” or “networks of traitors.” The lists may be one page, or they may be hundreds of pages. 
  3. Confirm their connection to the CIA, KGB, or the Vietnamese Military

“Neak thos” translates to “guilty person.” In Cambodian culture, the prisoners are “neak thos.” There is no presumption of innocence. But instead, imprisonment proved a person’s guilt. So prison guards and interrogators firmly believed in the guilt of every prisoner.

As a result of the prolonged torture, prisoners confessed to DK betrayal, espionage, or treacherous behavior. High target confessions included CIA, KGB, or Vietnamese military involvement. 

So, you can see this never-ending cycle. Interrogators feared for their own freedom if they couldn’t coerce confessions. Prisoners eventually experienced so much torture that they confessed to end the pain. And whether or not the admission held truth was immaterial as long as it was written and signed by the prisoner.

Torture instruments at Tuol Sleng Genocide Museum

  1. Beating with a stick. “The one that was used the most was beating with a stick because the others were time-wasting.” Kaing Guek Eav, AKA Dutch
  2. Electroshocks
  3. Suffocation with a plastic bag over the head
  4. Waterboarding. “Water was poured down a detainee’s nose,” Dutch said this technique was only attempted once. It was abandoned when the water “could not get through [the victim’s] nostrils.” 
  5. Medical experiments. “First, live prisoners were used for surgical study and training; second, blood drawing was also done,” Kaing Guek Eav, AKA Dutch.

Guards hung barbed wire across the 2nd and 3rd floor balconies, so prisoners could not jump to their deaths.

Torture Methods

Prak Khan is a former interrogator at S-21, who testified in 2009 to Cambodia’s UN-backed war crimes tribunal. These are some of his statements.

  • “Staff were taught to torture prisoners using electric shocks and suffocation.”
  • “We were taught how to torture the prisoners and to avoid the prisoners dying, otherwise, the confession would be broken, and we would be punished.”
  • “We were trained how to whip the prisoners with the sticks, on how to electrocute, (and) how to use the plastic bag to suffocate them.”
  • “We were taught a “light but painful” torture method in which they inserted a needle under prisoners’ nails.
  • Sometimes inmates were forced to eat excrement.
  • “Detainees would be told not to make loud noises, not to curse or exchange swear words, or to shout slogans. And they were also warned not to scream while being tortured.”
  • Occasionally, Khan witnessed medics extracting blood from prisoners until they died. “As I noted, there were five bags of blood taken from one detainee until the person was dying. After blood was drawn, no one could ever live because they were dying already while their blood was being taken.”
Ankle shackle
Prisoner bed shackle

Interrogator group types

Kaing Guek Eav, AKA Dutch, was questioned during Cambodia’s UN-backed war crimes tribunal. And he divided the interrogators into three distinct group types.

  1. “Cold.” No torture applied
  2. “Hot.” Would beat the prisoners immediately if the confessions were not extracted, as they wanted.
  3. “Chewing.” Subjected prisoners to long-term torture.

Execution at Tuol Sleng Genocide Museum

Once the prisoners confessed, the Khmer Rouge transferred them to Choeung Elk (The Killing Fields.) Execution via a shovel, knife or a sharp instrument occurred immediately upon arrival.

During S-21’s operations, eighteen thousand sixty-three prisoners experienced torture, interrogation, and execution.

And S-21 was only one of Cambodia’s 196 Khmer Rouge interrogation and detention facilities.  That took me a moment to fully comprehend. 18,063 souls from only this one high school turned prison.

S-21 site discovery

Early in 1979, the Vietnamese Military invaded Phenom Penh. The Khmer Rouge abandoned the building days before two Vietnamese photojournalists discovered the site. Unfortunately, they found S-21 by following the smell of decaying bodies. 

What did they find inside S-21?

The photojournalists found the corpses of fourteen recently murdered prisoners. And, sadly, some of the murdered prisoners remained chained to their beds while dried blood pooled on the floor beneath them.

Photograph of corpse found in this room shackled to this bed at Tuol Sleng Genocide Museum.
A moment in time captured

The photojournalists took pictures of the corpses. And you can see their photographs displayed in the same rooms where torture and death occurred. Looking at the pictures while standing in these high school classrooms turned torture chambers is hard. But it seems necessary, both as a way to remember and as a tribute to the lives lost.

Brick cell blocks
Prisoner cells constructed from brick

The second floor contained small, bricked cells built to house prisoners between interrogations. In addition, these tiny cells barely allowed room for lying down.

Wooden prisoner cells at Cambodia's Tuol Sleng Genocide Museum
Wooden prisoner cells on the third floor.

The third floor contained larger wooden cells. And you can see where guards created doorways in the classroom walls so a single person could watch over all the cells.

What makes S-21 different than other sites?

S-21 differs from other Khmer Rouge prisons because of the meticulous documentation found there.

  • Vietnamese Photojournalists discovered it before the Khmer Rouge destroyed the evidence.
  • The Photojournalists further documented what they saw.
  • The Khmer Rouge kept and left behind meticulous notes on all prisoners, including torture methods used.
    • Date of entry to S-21
    • Height
    • Weight
    • Confessions
    • Date of execution

Visiting Tuol Sleng Genocide Museum

Here are details for visiting S-21 Genocide Museum in Phnom Penh, Cambodia.

Open hours:

The museum is open daily from 8 AM to 5 PM. We toured the entire facility in approximately three hours. 

Official Website: https://tuolsleng.gov.kh/en/

Admission Cost (at time of our visit):

Adults (18 years and older): $5

Children (10-17 years of age): $3

Audio Tours:

A headset with multi-language audio: $5

We found the audio guide brought the experience to a different and more real level. Many of the display panels had a “primary” and “secondary” audio feed. The secondary audio allows the listener to hear more detailed information. 

And since you can choose which sections to listen to or bypass, just choose the primary feed if you’re short on time.

Keep in mind: 

Traveling to Tuol Sleng Genocide Museum on a tour bus may introduce scheduling “challenges”. And since the tour buses have an agenda to keep, it may equate to a shorter visit. Read Trip Advisor reviews for your best options and travel plans.

We took our time and wandered the entire facility without feeling rushed. And we recommend that you do the same, if possible. Honestly, it gave us time to process the horrors. But it seemed like the tour groups zipped through rather quickly.

Getting to Tuol Sleng Genocide Museum:

We hopped on a tuk-tuk from our hotel to S-21 for $3. However, you can catch a Grab Taxi as well. But tuk-tuks are cheap and readily available. And riding in them is its own experience, so don’t hesitate to use one.

It's easy to find a Tuk-Tuk in Cambodia. Make sure to negotiate the price before you get into the Tuk-Tuk
Cambodia Tuk-Tuk


Tuol Sleng Genocide MuseumStreet 113, Sangkat Boeung Keng Kang 3, Khan Boeung Keng KangPhnom Penh


Email info@tuolsleng.gov.khPhone 023 6 555 395/077 252 121

Cambodia Guidebooks We Love

As an Amazon Associate, we earn from qualifying purchases. This page contains affiliate links, so if you choose to purchase after clicking a link, we may receive a commission at no extra cost to you. We appreciate you supporting us in this small way.

National Geographic Traveler Cambodia

Lonely Planet Pocket Siem Reap & the Temples of Angkor 3 (Pocket Guide) Paperback

Survivor Chum Mey with Documentation Center of Cambodia

Bou Meng Survivor by Huy Vannak


  1. Shar

    The ugly parts of humanity is heartbreaking.

    • mcgarveysan

      It is heartbreaking. And it is ugly. I guess it’s good for us to remember, even though we still seem doomed to repeat…

  2. Angus Mccamant

    Wow. Thanks for the thorough review of history. I remember that time, we knew what was going on but there was no national incentive to put an end to the violence, we just ignored it.

    Thanks for the post.

    • mcgarveysan

      I remember that time too, but was young and didn’t realize what was really happening. I think the US didn’t publicize it much because of our roll in helping create an environment which allowed something like this to occur. Thanks for reading.


Submit a Comment

Your email address will not be published. Required fields are marked *