Women in China's "re-education" camps for Uighurs have been systematically raped, sexually abused, and tortured, according to detailed new accounts obtained by the BBC.
You may find some of the details in this story distressing.
Tursunay Ziawudun spent nine months inside China's network of internment camps.
The men always wore masks, Tursunay Ziawudun said, even though there was no pandemic then.
They wore suits, she said, not police uniforms.
Sometime after midnight, they came to the cells to select the women they wanted and took them down the corridor to a "black room", where there were no surveillance cameras.
Several nights, Ziawudun said, they took her.
"Perhaps this is the most unforgettable scar on me forever," she said.
"I don't even want these words to spill from my mouth."
Tursunay Ziawudun spent nine months inside China's vast and secretive system of internment camps in the Xinjiang region. According to independent estimates, more than a million men and women have been detained in the sprawling network of camps, which China says exist for the "re-education" of the Uighurs and other minorities.
Human rights groups say the Chinese government has gradually stripped away the religious and other freedoms of the Uighurs, culminating in an oppressive system of mass surveillance, detention, indoctrination, and even forced sterilisation.
The policy flows from China's President, Xi Jinping, who visited Xinjiang in 2014 in the wake of a terror attack by Uighur separatists. Shortly after, according to documents leaked to the New York Times, he directed local officials to respond with "absolutely no mercy". The US government said last month that China's actions since amounted to a genocide. China says reports of mass detention and forced sterilisation are "lies and absurd allegations".
First-hand accounts from inside the internment camps are rare, but several former detainees and a guard have told the BBC they experienced or saw evidence of an organised system of mass rape, sexual abuse and torture.
Tursunay Ziawudun, who fled Xinjiang after her release and is now in the US, said women were removed from the cells "every night" and raped by one or more masked Chinese men. She said she was tortured and later gang-raped on three occasions, each time by two or three men.
Ziawudun has spoken to the media before, but only from Kazakhstan, where she "lived in constant fear of being sent back to China", she said. She said she believed that if she revealed the extent of the sexual abuse she had experienced and seen, and was returned to Xinjiang, she would be punished more harshly than before. And she was ashamed, she said.
Tursunay Ziawudun was able to flee to Kazakhstan, and then on to relative safety in the US.
It is impossible to verify Ziawudun's account completely because of the severe restrictions China places on reporters in the country, but travel documents and immigration records she provided to the BBC corroborate the timeline of her story. Her descriptions of the camp in Xinyuan county - known in Uighur as Kunes county - match satellite imagery analysed by the BBC, and her descriptions of daily life inside the camp, as well as the nature and methods of the abuse, correspond with other accounts from former detainees.
Internal documents from the Kunes county justice system from 2017 and 2018, provided to the BBC by Adrian Zenz, a leading expert on China's policies in Xinjiang, detail planning and spending for "transformation through education" of "key groups" - a common euphemism in China for the indoctrination of the Uighurs. In one Kunes document, the "education" process is described as "washing brains, cleansing hearts, strengthening righteousness and eliminating evil".
The BBC also interviewed a Kazakh woman from Xinjiang who was detained for 18 months in the camp system, who said she was forced to strip Uighur women naked and handcuff them, before leaving them alone with Chinese men. Afterwards, she cleaned the rooms, she said.
"My job was to remove their clothes above the waist and handcuff them so they cannot move," said Gulzira Auelkhan, crossing her wrists behind her head to demonstrate. "Then I would leave the women in the room and a man would enter - some Chinese man from outside or policeman. I sat silently next to the door, and when the man left the room I took the woman for a shower."
The Chinese men "would pay money to have their pick of the prettiest young inmates", she said.
Some former detainees of the camps have described being forced to assist guards or face punishment. Auelkhan said she was powerless to resist or intervene.
Asked if there was a system of organised rape, she said: "Yes, rape."
"They forced me to go into that room," she said. "They forced me to take off those women's clothes and to restrain their hands and leave the room."
Some of the women who were taken away from the cells at night were never returned, Ziawudun said. Those who were brought back were threatened against telling others in the cell what had happened to them.
"You can't tell anyone what happened, you can only lie down quietly," she said. "It is designed to destroy everyone's spirit."
Mr Zenz told the BBC that the testimony gathered for this story was "some of the most horrendous evidence I have seen since the atrocity began".
"This confirms the very worst of what we have heard before," he said. "It provides authoritative and detailed evidence of sexual abuse and torture at a level clearly greater than what we had assumed."
Gulzira Auelkhan makes tea at home in her village. She was detained for 18 months. (Getty Images)
The Uighurs are a mostly Muslim Turkic minority group that number about 11 million in Xinjiang in north-western China. The region borders Kazakhstan and is also home to ethnic Kazakhs. Ziawudun, who is 42, is Uighur. Her husband is a Kazakh.
The couple returned to Xinjiang in late 2016 after a five-year stay in Kazakhstan, and were interrogated on arrival and had their passports confiscated, Ziawudun said. A few months later, she was told by police to attend a meeting alongside other Uighurs and Kazakhs and the group was rounded up and detained.
Her first stint in detention was comparatively easy, she said, with decent food and access to her phone. After a month she developed stomach ulcers and was released. Her husband's passport was returned and he went back to Kazakhstan to work, but authorities kept Ziawudun's, trapping her in Xinjiang. Reports suggest China has purposefully kept behind and interned relatives to discourage those who leave from speaking out. On 9 March 2018, with her husband still in Kazakhstan, Ziawudun was instructed to report to a local police station, she said. She was told she needed "more education".
According to her account, Ziawudun was transported back to the same facility as her previous detention, in Kunes county, but the site had been significantly developed, she said. Buses were lined up outside offloading new detainees "non-stop".
The women had their jewelry confiscated. Ziawudun's earrings were yanked out, she said, causing her ears to bleed, and she was herded into a room with a group of women. Among them was an elderly woman who Ziawudun would later befriend.
The camp guards pulled off the woman's headscarf, Ziawudun said, and shouted at her for wearing a long dress - one of a list of religious expressions that became arrestable offences for Uighurs that year.
"They stripped everything off the elderly lady, leaving her with just her underwear. She was so embarrassed that she tried to cover herself with her arms," Ziawudun said.
"I cried so much watching the way they treated her. Her tears fell like rain."
Ziawudun identified this site - listed as a school - as the location where she was held. Satellite images from 2017 (left) and 2019 (right) show significant development typical of camps, with what look like dormitory and factory buildings. (Maxar)
The women were told to hand over their shoes and any clothes with elastic or buttons, Ziawudun said, then taken to cellblocks - "similar to a small Chinese neighbourhood where there are rows of buildings".
Nothing much happened for the first month or two. They were forced to watch propaganda programmes in their cells and had their hair forcibly cut short.
Then police began interrogating Ziawudun about her absent husband, she said, knocking her on the floor when she resisted and kicking her in the abdomen.
"Police boots are very hard and heavy, so at first I thought he was beating me with something," she said. "Then I realised that he was trampling on my belly. I almost passed out - I felt a hot flush go through me."
A camp doctor told her she might have a blood clot. When her cellmates drew attention to the fact that she was bleeding, the guards "replied saying it is normal for women to bleed", she said.
According to Ziawudun, each cell was home to 14 women, with bunk beds, bars on the windows, a basin and a hole-in-the-floor-style toilet. When she first saw women being taken out of the cell at night, she didn't understand why, she said. She thought they were being moved elsewhere.
Secret filming obtained by the Bitter Winter activist group showed cells with bars and cameras.
Then sometime in May 2018 - "I don't remember the exact date, because you don't remember the dates inside there" - Ziawudun and a cellmate, a woman in her twenties, were taken out at night and presented to a Chinese man in a mask, she said. Her cellmate was taken into a separate room.
"As soon as she went inside she started screaming," Ziawudun said. "I don't know how to explain to you, I thought they were torturing her. I never thought about them raping."
The woman who had brought them from the cells told the men about Ziawudun's recent bleeding.
"After the woman spoke about my condition, the Chinese man swore at her. The man with the mask said 'Take her to the dark room'.
"The woman took me to the room next to where the other girl had been taken in. They had an electric stick, I didn't know what it was, and it was pushed inside my genital tract, torturing me with an electric shock."
Ziawudun's torture that first night in the dark room eventually came to an end, she said, when the woman intervened again citing her medical condition, and she was returned to the cell.
About an hour later, her cellmate was brought back.
"The girl became completely different after that, she wouldn't speak to anyone, she sat quietly staring as if in a trance," Ziawudun said. "There were many people in those cells who lost their minds."
Gulzira Auelkhan, centre, at home in her village. She was forced to restrain women in the camps, she said. (Getty)
Alongside cells, another central feature of the camps is classrooms. Teachers have been drafted in to "re-educate" the detainees - a process activists say is designed to strip the Uighurs and other minorities of their culture, language and religion, and indoctrinate them into mainstream Chinese culture.
Qelbinur Sedik, an Uzbek woman from Xinjiang, was among the Chinese language teachers brought into the camps and coerced into giving lessons to the detainees. Sedik has since fled China and spoken publicly about her experience.
The women's camp was "tightly controlled", Sedik told the BBC. But she heard stories, she said - signs and rumours of rape. One day, Sedik cautiously approached a Chinese camp policewoman she knew.
"I asked her, 'I have been hearing some terrible stories about rape, do you know about it?' She said we should talk in the courtyard during lunch.
"So I went to the courtyard, where there were not many cameras. She said, 'Yes, the rape has become a culture. It is gang rape and the Chinese police not only rape them but also electrocute them. They are subject to horrific torture.'"
That night Sedik didn't sleep at all, she said. "I was thinking about my daughter who was studying abroad and I cried all night."
Sayragul Sauytbay, a teacher, said she witnessed a harrowing rape. She was later accused of crossing illegally into Kazakhstan. (Getty Images)
In separate testimony to the Uyghur Human Rights Project, Sedik said she heard about an electrified stick being inserted into women to torture them - echoing the experience Ziawudun described.
There were "four kinds of electric shock", Sedik said - "the chair, the glove, the helmet, and anal rape with a stick".
"The screams echoed throughout the building," she said. "I could hear them during lunch and sometimes when I was in class."
Another teacher forced to work in the camps, Sayragul Sauytbay, told the BBC that "rape was common" and the guards "picked the girls and young women they wanted and took them away".
She described witnessing a harrowing public gang rape of a woman of just 20 or 21, who was brought before about 100 other detainees to make a forced confession.
"After that, in front of everyone, the police took turns to rape her," Sauytbay said.
"While carrying out this test, they watched people closely and picked out anyone who resisted, clenched their fists, closed their eyes, or looked away, and took them for punishment."
The young woman cried out for help, Sauytbay said.
"It was absolutely horrendous," she said. "I felt I had died. I was dead."
Ziawudun broke down in tears as she identified footage and images of the camps.
In the camp in Kunes, Ziawudun's days drifted into weeks and then months. The detainees' hair was cut, they went to class, they underwent unexplained medical tests, took pills, and were forcibly injected every 15 days with a "vaccine" that brought on nausea and numbness.
Women were forcibly fitted with IUDs or sterilised, Ziawudun said, including a woman who was just about 20 years old. ("We begged them on her behalf," she said.) Forced sterilisation of Uighurs has been widespread in Xinjiang, according to a recent investigation by the Associated Press. The Chinese government told the BBC the allegations were "completely unfounded&quo