Yang Maodong was missing for about a month before his loved ones were told he had been arrested by China's police.
Better known by his pen name Guo Feixiong, he vanished in early December after writing a public letter asking to be allowed to travel to the US to care for his wife, who had been diagnosed with colon cancer.
He texted a friend, "I'm being arrested", and hasn't been heard from since.
His family and friends assumed he had been detained, until the authorities finally confirmed earlier this month that he had been arrested on "suspicion of inciting subversion of state power".
Zhang Qing, his wife, died from cancer last week without being able to say goodbye to her husband.
The lawyer and activist is just one of the many people "disappeared" in China that rarely get mentioned in mainstream media.
While people were asking #WhereisPengShuai, many others who have been "disappeared" were not receiving the same attention from the international community, according to Human Rights Watch senior researcher Wang Yaqiu.
According to Spain-based rights group Safeguard Defenders, thousands of people are taken into custody in this manner every year.
"Collecting the data that is available and analysing the trends, the estimate is every year 4,000 to 5,000 people are disappeared into the RSDL [residential surveillance at a designated location] system alone," the group's co-founder Michael Caster told Al Jazeera.
'Residential surveillance at a designated location'
Ms Peng disappeared from public view for two weeks in November after detailing in a quickly-deleted social media post her allegedly abusive secret relationship with a former top Communist Party official.
It prompted an outpouring of concern from athletes, sports organisations, human rights advocacy groups and even governments.
Ms Wang said despite claims by China's state-owned media and "friends" in China that Ms Peng was safe, she was still far from having total freedom.
"After what happened, as long as she still lives in China, she for sure wouldn't be able to have the freedom we broadly define as freedom of movement and freedom of speech," Ms Wang said.
It's not clear what happened to Ms Peng during the two weeks she disappeared from public view.
However, Ms Wang said her profile afforded her a measure of protection.
"The intense international attention made the Chinese government much more careful about what they decide to do with her," Ms Wang said.
"Sexual assault [allegations have] wide support among the public, especially women.
"[But] after what happened, as long as she still lives in China, she for sure wouldn't be able to have the freedom we broadly defined as freedom of movement and freedom of speech."
Others, like Mr Yang, were left in much worse situations when they were "disappeared", Ms Wang said.
Many were secretly sequestered into "residential surveillance at a designated location" (RSDL) before any charges were laid and where the treatment they received could be worse than in traditional prisons.
While legislated under Chinese law, RSDL is not part of the formal judicial process for a suspect.
Instead, it is an initial six-month period when investigators can detain suspects incommunicado at "black jails", interrogating them, gathering evidence and building a case without needing to charge them or obtain a court's permission.
When asked about missing Australians before they were formally detained, China's Foreign Ministry has previously told the ABC it did not have information about their cases and that the relevant department would "act according to the law".
A 'great leap backwards'
According to a recent report from Reporters Without Borders titled "A great leap backwards in journalism", China is the world's biggest captor of journalists with at least 127 reporters in detention.
Among those who have been "disappeared" by the Chinese authorities include Haze Fan, a Chinese national reporting for Bloomberg in Beijing, and her friend Australian journalist Cheng Lei.
Ms Fan was detained in December 2020, four months after Ms Cheng was detained — both for allegedly "endangering national security".
According to Bloomberg, Ms Fan was last seen on December 7, 2020, when she was escorted by national security officers from her apartment, and the authorities have provided no information about her status since.
Citizen journalists have also been targeted, such as Zhang Zhan and Fang Bin, who were detained while trying to inform the public about the COVID-19 situation in Wuhan early in the pandemic.
Chinese #MeToo activist Huang Xueqin, who is also a journalist, went missing in September last year when she was about to leave via Hong Kong for Britain to study.
A friend of hers, labour activist Wang Jianbing, who was seeing her off, also "disappeared".
In November, their families reportedly received notice of their arrest, which accused them of allegedly "inciting subversion of state power".
Ms Huang's coverage of a high-profile university professor allegedly committing sexual assaults over years against his students was the start of China's #MeToo movement in 2017.
She was also involved in activism helping victims of sexual assault across China.
In 2019, Ms Huang attended Hong Kong's anti-extradition law protests and wrote about them online, which led to her being accused of "picking quarrels and provoking trouble" and three months in detention.
Amnesty International reported that both Ms Huang and Mr Wang were not allowed to choose their own lawyer or see family members. Several of their friends also had their homes searched and devices confiscated.
While calling on the release of the two, Amnesty International China Campaigner Gwen Lee said Ms Huang's arrest exemplified the Chinese authorities' hostility towards journalists who dared to report the truth.
Mystery detentions
Sometimes it's not clear why people are "disappeared" in China.
Fang Ran, a Hong Kong University PhD student and labour rights researcher, went missing last year while visiting home in the Guangxi region.
A widely-circulated letter posted by Mr Fang's father Fang Jianzhong said he was in pain every day and cried out for help for his son.
In the letter, the father said Fang Ran was taken away by national security officers and was being held in "residential surveillance at a designated location".
"It was a big shock for me," Fang Jianzhong wrote.
"He has been focused on completing his studies in the past two years … Fang Ran has zero motive, nor does he have any grounds to conduct activities against the law or disrupt the society."
Ms Wang, the HRW researcher, questioned how much "danger" Mr Fang's research could have posed.
She said the peril behind arbitrary detention was that it was hard to predict what was actually leading to a disappearance.
"You never know what exactly is the reason [behind the detention]. And it's difficult to evaluate your risk," she said.
"You are [usually] safe if you never spoke a bad word of the Communist Party, but if you did it once, somewhere, then there is a risk."
Chasing freedom is 'dangerous'
A long-time human rights defender, Mr Yang had already served two long stints in jail for his advocacy before his disappearance last month.
His daughter, Yang Tianjiao, said she had not seen him since he was jailed in 2007 after he wrote a book about a political corruption scandal and was convicted of "illegal business activity".
The ABC has been unable to reach Ms Yang since her mother's death last week, but she previously said she rarely saw her father, even before his arrest.
"When he was home, he just sat there writing for days on end," Ms Yang told the ABC.
Under constant surveillance by the authorities, Ms Yang fled the country with her brother and mother and received asylum in the US in 2009.
"You public servants are also husbands, [blessed with] marital love, must also have empathy of ordinary people," Mr Yang wrote in his open letter to China's Premier Li Keqiang in January 2021, asking for permission to go to the US when he first learned of his wife's diagnosis.
Before her mother's death, Ms Yang said the pursuit of freedom was always important to her father.
"Everyone's free here, but in China back then, chasing freedom was dangerous and it still is," she said.
