Zumrat Dawut was at her home in northwestern China in March 2018 when she received a phone call instructing her to report to the local police station.

In the previous year, Dawut said she, like countless other Uighurs in China, had her passport confiscated, her DNA sampled, and spyware downloaded onto her phone. Calls like this one were frightening but increasingly routine.

“I told my kids that the police called me, but I’ll be back,” recalled Dawut, 37, a mother of three from Urumqi. “I didn’t even dress up. I wore my slippers.”

Dawut didn't return home that day. Or the next day. Or the next.

At the police station, officers grilled her about her international travel and phone calls, Dawut said, and refused to believe they were related to her family’s import-export business.

After several hours, officers placed shackles on her wrists and ankles. They put a black hood over her head. And then, she said, they transported her to a “re-education” camp.

Dawut had become one of the estimated 1 million people swept into China’s network of Muslim internment centers.

For at least the last three years, Chinese authorities in the far western region of Xinjiang have been rounding up men and women — largely Muslims of the Uighur, Kazakh and Kyrgyz ethnic minorities — and detaining them in camps designed to rid them of terrorist or extremist leanings. After repeated denials, Chinese authorities began acknowledging the existence of the camps in the latter half of 2018 but framed them as vocational training centers for the unemployed and in some cases as boarding schools.

Jiachuan Wu / NBC News

A cache of internal government documents — most signed by the then-No. 2 Communist Party official in Xinjiang — tells a different story.

The leaked records include a memo laying out protocols for facilities that more closely resemble prisons focused on indoctrinating detainees. Preventing escapes is paramount, the documents say, and a chief goal of the camps is “ideological transformation.”

The memo — dated 2017 when the internment campaign was gaining momentum — details how the camps are meant to be run, from the banality of monitoring bathroom breaks to the importance of having in place “one-button alarms” and other security measures.

The leaked records also provide a window into China’s high-tech surveillance system, whom it is tracking, and how it is being used to identify candidates for “re-education.” NBC News is reporting on the previously undisclosed documents, obtained by the International Consortium of Investigative Journalists, together with 17 news organizations around the world.

The 24 pages of documents offer unprecedented insight into China’s mass detention of Uighurs and other Muslim minorities in western China. They corroborate evidence previously pieced together by researchers and media organizations — satellite imagery, regional security budgets and eyewitness testimony — that China is running a vast network of re-education camps.

Experts said the leak of the materials amounts to an extraordinary breach in a country known for crushing dissent.

“In Xinjiang, people have been sentenced to death for much less than this,” said Adrian Zenz, a German researcher considered one of the foremost authorities on China’s detention of ethnic minorities.

Zenz describes the camps as “political brainwashing centers.”

“The Chinese know that what they’re doing in these camps is like the Cultural Revolution on steroids,” he added. “And they want to hide this, especially from the Muslim world.”

“Ideological transformation”

Xinjiang is home to at least 10 million Uighurs, an ethnic minority of Turkic Muslims whose language and traditions are distinct from mainstream Chinese culture.

Since the first reports of China’s mass detention of Muslims emerged a few years ago, it’s been nearly impossible to verify what goes on inside the camps. Some foreign officials and media outlets, including NBC News, have been granted highly controlled tours, but they have largely presented a picture at odds with the stories of Uighurs and other Muslims who have experienced them.

The newly revealed documents show that not only were senior Xinjiang officials aware of what was happening in the camps in 2017, but also that the sites were designed at the outset as high-security facilities for the purpose of indoctrination.

In addition to the operational memo and the surveillance bulletins, both dated 2017, the leaked documents include a 2018 court record that describes the case of a Uighur man sentenced to prison for encouraging his co-workers to become better Muslims by avoiding such behavior as using foul language.

Both the memo and bulletins were signed by Zhu Hailun, then the second in command of the ruling Communist party in Xinjiang, and the region’s top security chief. The documents are also classified “secret,” the second highest security classification in China. The classification refers to documents that hold “important national secrets,” Zenz explained, the disclosure of which “would cause serious harm to national security.”

In contrast to the Chinese government’s public statements, the memo shows that vocational training was always meant to be a facet of the re-education camps, but not their focus. “Ideological transformation” is listed as the first basis of assessment in a ranking system that determines “rewards, punishments and family visits.”

The memo goes on to outline a timeline for re-education — “students” have to be re-educated for at least one year and have met the standard for “ideological transformation” before they can graduate to “vocational skills improvement class” for an additional three to six months.

Experts say the vocational skills component amounts to coerced factory labor where the detainees are paid a pittance.

Zenz said this refers to any religious activity. “They’re trying to get the students to think: ‘You have a belief in Islam. You have read the Quran. That’s evil. That’s bad,’” Zenz said.

The Chinese government called the leaked documents “pure fabrication and fake news.” “There are no so-called ‘detention camps’ in Xinjiang,” the press office for China’s U.K. embassy said in a statement. “Vocational education and training centers have been established for the prevention of terrorism.”

“If suspicion cannot be ruled out…”

The leaked bulletins come from the “Integrated Joint Operations Platform,” a surveillance dragnet used by the Chinese government to collect a stunning array of data on people in Xinjiang — everything from education levels and travel histories to their blood type.

In addition to surveilling users of a smartphone app called Zapya, a wireless file sharing program used at one time by nearly 2 million Uighurs in Xinjiang, the government monitors dual citizens, including Americans, the documents show.

One bulletin provides details on the surveillance of people from Xinjiang who gained citizenship elsewhere and sought visas to return to China. The bulletin from June 2017 shows Chinese authorities identified at least 75 such people living in China, including three Americans.

David Stillwell, the assistant secretary of state for East Asia, said it is “unnerving” that China is tracking Americans. He added that the U.S. has no doubt about what’s driving China’s campaign against its ethnic Muslim minorities.

“The fact is that you have people that are held against their will for the crime of believing in Islam,” Stillwell said.

The bulletins also hint at the scope of the dragnet. In four Uighur-majority prefectures in southern Xinjiang, more than 24,000 people were deemed “suspicious” and over 15,000 of them were sent to re-education camps during one week in June 2017, one bulletin says.

A police officer stands by the road near what is officially called a vocational education center in Yining in Xinjiang, China, on Sept. 4, 2018. Thomas Peter / Reuters

“The Chinese have bought into a model of policing where they believe that through the collection of large-scale data, run through artificial intelligence and machine learning, that they can in fact predict ahead of time where possible incidents might take place,” said James Mulvenon, an expert on China's security apparatus.

“They are pre-emptively going after those people, using that data, before they’ve even had a chance to actually commit the crime.”

The Chinese government published a white paper in August outlining three kinds of people that should face re-education: those who participate in extremist activities “not serious enough to constitute a crime,” those whose activities “posed a real danger but did not cause actual harm,” and those who served time for terrorism and still pose “a potential threat to society.”

The problem, critics say, is Chinese officials take a deliberately broad view of what constitutes “extremist activities” in Xinjiang.

“What are the illegal religious activities? Eating halal food? Refusing to eat pork? Refusing to drink alcohol? People fasting during Ramadan?” said Rushan Abbas, a Uighur-American activist who has more than two dozen relatives she believes are currently detained in the camps.

Rushan Abbas, a Uighur-American activist, has more than two dozen relatives she believes are currently detained in the camps. Hannah Rappleye / NBC News

“What kind of national security that people not eating pork has to do with being radicalized or being a threat to the society? It's all lies, it's just a pretext they are using.”

Abbas said her sister, a retired medical doctor, was detained even though she doesn’t engage in any religious activities and speaks fluent Chinese.

“She doesn't fast. She doesn't go to mosque. She doesn't pray,” Abbas said.

“He was easily susceptible to being misguided…”

The vast majority of the estimated more than 1 million Muslims held in extrajudicial internment in camps in Xinjiang have not been charged or convicted of crimes, experts say.

But the push to detain massive numbers of Uighurs and other ethnic minorities came at the same time as the police ramped up criminal arrests in the region.

Criminal arrests in Xinjiang 2015-2018

Published government data shows a dramatic increase in criminal arrests during the time Xinjiang expanded its efforts to crackdown on Muslim minorities in the region.

Sources: Xinjiang People's Procuratorate Annual Work Reports, The Network of Chinese Human Rights Defenders (CHRD) Report Jiachuan Wu / NBC News

The document related to the court case of a Uighur man sheds light on the type of behavior that can lead to a stiff prison sentence.

The case file, written in Uighur, shows the man was sentenced to 10 years in prison for telling his fellow Uighur co-workers that it is not proper for Muslims to use foul language or watch pornography, and for urging them to eat halal food, which is prepared according to religious guidelines. The case file says the man dismissed Muslims who do not follow these practices as no better than nonbelievers.

He was convicted of “incitement of ethnic hatred and ethnic discrimination,” the documents says.

The man’s defense attorney didn’t contest the charges, but sought leniency from the judges. “Due to the defendant’s low legal awareness and education level, he was easily susceptible to being misguided and committing crimes,” the lawyer told the court, according to the case file. “He’s guilty.”

Recently, government officials have doubled down on their defense of the camps, relying on two arguments: that they are lifting people out of poverty by teaching them valuable skills, and that the camps are necessary to keep dangerous extremists off the streets.

In September, on the sidelines of the U.N. General Assembly, Chinese Foreign Minister Wang Yi touted that China hasn’t had a terror incident in three years, and said the camps are helping “people free themselves from terrorism and extremism.”

Survivors of the camps, or “graduates” as the Chinese government refers to them, paint a very different picture than the one pushed by Chinese officials publicly. Their stories do, however, corroborate many key points in the memo outlining the camps’ operational instructions.

“How can a human live this way”

Gulbakhar Jalilova said she was picked up by plainclothes policemen at a hotel in Urumqi in May 2017. A single mother of three from Kazakhstan, Jalilova traveled to China on a work trip for her children’s jewelry business.

As a foreigner of Uighur ethnicity doing business in China, Jalilova was likely being tracked by authorities long before she arrived in the country.

After she was arrested, Jalilova said in an interview, she was interrogated for hours and pressured to sign a statement saying she had sent a large sum of money to Turkey.

She was placed in a windowless cement room with other female detainees. Four surveillance cameras hung from the walls and a TV screen was mounted in the front of the room that showed only President Xi Jinping speeches and Communist party videos.

Robin Muccari / NBC News

Jalilova said they were fed meals of watery soup and bread. As the days turned to weeks, she said, her body began wasting away.

In addition to learning Chinese and singing party songs, they were also ordered to write letters repenting for past behavior, Jalilova said, even if they didn’t have anything to repent for.

“I don't have any connection with terrorism,” she said, speaking through a Uighur interpreter. “Did I pray? Did they find any religious books with me? No. If they found something like that, they would have sentenced me to prison.”

Some parts of Jalilova’s experience show that not all of the directives in the classified memo were put into practice. While the memo says that detainees should be taught good hygiene, Jalilova recounted grim conditions.

Jalilova said the women were given two minutes per month to shower, and were never given fresh underwear. Skin sores and rashes were common, and when the women got lice, she said the guards simply shaved their heads.

Gulbakhar Jalilova in Istanbul on Nov. 16, 2018. Murad Sezer / Reuters

“How can a human live this way?” Jalilova said.

The memo also says that detainees should be allowed one phone call per week and one video call per month to their families. Jalilova, like many other former detainees, said she was not once allowed to contact her family during the entire 15 months she was detained.

Jalilova was finally released in September 2018.

The police took her to a prison hospital where she received three days of treatment, including a gradual introduction to heavier food. On the third day, a police officer handed over her clothes and applied make-up to her face, Jalilova said, before escorting her to the airport for a flight back to Kazakhstan.

When her children first laid eyes on her, they nearly didn’t recognize her. Jalilova said she had lost almost 30 pounds in detention.

Jalilova reunited with her children. Courtesy Gulbakhar Jalilova

“My elder daughter was scared when she saw me,” said Jalilova, who now lives in Istanbul. “I was so skinny at that time, my daughter cried.”

The police had handed over her passport and cellphone with specific instructions, Jalilova said.

“They said: ‘Do your business as usual. You can come back to China, but forget about what happened here. Don’t tell anyone,’” she said.

Dawut, the mother who left her home in slippers after receiving a call from police, arrived at a camp six months earlier. Once inside, she said, two guards escorted her down a long corridor and gave her a stern talk.

“The guards told me that I must obey every rule at the center,” she said. “And I cannot speak to anyone. I cannot cry. There are four cameras in each room so they can see any action.”

Zumrat Dawut at her home in northern Virginia, on Nov. 18, 2019. Cheryl Diaz Meyer / for NBC News

When she got to the room, there were roughly 40 women inside, some as young as 16 and as old as 80. The first thing she noticed was the smell of unwashed bodies. The room itself was so crowded the women had to sleep in shifts, she said. “People had to stand so the others can lay down and sleep,” she said.

It was here where she spent the night for the next two months.

In the mornings, loud music would sound signaling that water would run from single spout in the room. “We must wake up immediately,” Dawut said. “The water will rush out for a really short time. Everyone must act very quickly, otherwise they don’t have water to wash.”

Before breakfast, detainees would have to praise President Xi and the Communist Party. Then they would be taken to a classroom where they would sit on the floor, surrounded by guards, to learn Chinese and listen to a teacher recite communist propaganda.

“They used to explain that our religion came from another country, not native to our land and people,” Dawut said. “It’s a kind of ideological disease.”

All the while, Dawut said, they lived under the constant threat of punishment. It wasn’t unusual to hear distant screaming or crying reverberating through the walls, she said. One time, she faced it herself.

Dawut said one of her fellow detainees was an older woman who suffered from diabetes but had no access to insulin. “She was suffering all the time,” Dawut said, “and she couldn’t sleep.”

Feeling pity for her, Dawut gave the woman her piece of bread, but she said her act of kindness was caught on surveillance cameras and seen by the guards.

“The guard came with a long rubber baton, and they began to beat me, and beat me so hard that I couldn’t stand up,” Dawut recalled as tears streamed down her cheeks onto her shirt.

For all her husband knew, Dawut had simply vanished.

He was running an errand to the bank when she left their home for the police station and disappeared into the detention camp.

With no idea where she was, Dawut’s husband, who is Pakistani, went from police station to police station looking for her. But he received no answers.

A few weeks later, he and their children were called to a government office to hold a video chat with Dawut. The opportunity to communicate with her family was a reward for her good behavior.

In the camp, Dawut said, a point system was used to determine rewards and punishments. Dawut said she received points for such acts as arriving in a classroom on time, swallowing pills that made her feel dazed and numb, and refraining from sharing food.

The classified documents show the point system was formalized. In a section of the memo called “Point Management,” camp staff are instructed to grade detainees “ideological transformation” and “compliance with discipline.”

Prior to the call, Dawut was brought to a special room in the camp and made up with lipstick and foundation. “They ordered us to smile the whole time. We cannot say anything and we cannot reveal our sadness,” she said.

Dawut’s family had not told her children where she was. “My small girl, she was asking me: ‘Did you abandon us? Why are you not taking care of us? Why didn’t you come back?’” a weeping Dawut recalled.

Dawut with her three children at home in northern Virginia, on Nov. 18, 2019. Cheryl Diaz Meyer / for NBC News

Some weeks later, Dawut’s husband gathered in Beijing with other Pakistani men whose wives disappeared into the camps. Soon after they approached the media, Dawut’s husband and the others received a call from the police telling them to return to Xinjiang.

Dawut was released the next day, in June 2018. She said she was forced to sign a form saying that she went to the camp voluntarily. “They demanded that we are not going to tell anything about the education center,” she said. “They called it the education center.”

Still under strict surveillance, her family made preparations to leave China. They traveled to Pakistan under the pretense that the family had to care for Dawut’s sick father-in-law.

But in Pakistan, Dawut still didn’t feel safe, so they flew to the U.S. on tourist visas they had received before the crackdown in Xinjiang.

The family arrived in April and settled in Virginia. They have since filed for asylum and are hoping to remain in the U.S. as political refugees.

Zumrat Dawut at home with her son. Cheryl Diaz Meyer / for NBC News

Nearly 18 months after her release from detention, Dawut still bristles at the Chinese government’s claims that the camps help alleviate poverty and rid people of the seeds of extremism.

“This was prison. That’s what it was,” Dawut said in an interview at her home.

“If it was even partially for the purpose of re-educating, then they wouldn’t have chained all of us, or hit us, or tortured us, or pressured us. If it was for educational purposes they would have allowed us to go home, and go in for lessons for two hours every day. Not separate us from our families, our children, our parents.”

This story by NBC News is part of a collaboration with the International Consortium of Investigative Journalists, a nonprofit organization based in Washington. The partnership includes more than 75 journalists at 17 news organizations in 14 countries.