It's not often that the governments of major nations are so concerned about hunting down the authors of anonymous online letters.
But that is what's happening in China, as police have detained and questioned journalists and the families in China of overseas dissidents, in an apparent effort to find out who wrote a letter calling for President Xi Jinping to step down.
The incident is the latest chapter in a heated debate about the limits of free speech, under a leader who has tried to accumulate personal power and enforce ideological conformity far more than any of his recent predecessors.
The letter criticized precisely these actions. Claiming to speak for "loyal party members," it argued that Xi's personal accumulation of power had undermined the "collective leadership" of Communist Party elites and "weakened the power of all state organs."
It added that Xi's personal involvement in economic policymaking had caused volatility in financial markets, while his assertive foreign policies had antagonized China's neighbors. Other critics have leveled similar charges, but haven't gone so far as to call for Xi's resignation.
The letter urged Xi to resign for the sake of national stability, "and for your own personal safety and that of your family."
It was posted on overseas and Chinese websites on March 3, as legislators gathered in Beijing for the annual session of the National People's Congress.
Editors and managers at Watching.cn, a website backed by the Communist Party committee of the western region of Xinjiang and other investors, were the first to disappear after the website ran the letter.
Next, a freelance author named Jia Jia linked to one of the website's managers was detained at the Beijing airport as he tried to leave for Hong Kong. He was released on Friday.
On March 22, authorities in southern China also detained the parents and younger brother of Wen Yunchao, a New York-based blogger and activist.
Authorities' aim was apparently "to force me to cooperate with their investigation into this open letter," Wen said, speaking by phone from New York, "or even to force me to admit that I was involved with it."
"But I can't admit to something that has nothing to do with me," he added.
Wen said that his brother's wife went to local police to inquire about her husband's whereabouts, but was told that "they weren't handling this case, and they didn't know where this person is."
Wen said he believes that authorities have set up "a high-ranking task force" to handle the case.
Authorities also reportedly arrested relatives of Germany-based commentator and journalist Zhang Ping, who goes by the pen name Chang Ping, and told them to warn Zhang to stop criticizing the Communist Party and writing about the letter.
The hunt for the letter's author comes as Xi's first five-year term is drawing to a close. He is expected to get a second and final one at a Communist Party congress next year.
Xi has called for rank-and-file Communist Party members to avoid questioning central government policies, and for state-run media to unfailingly promote the party's views.
One brash real estate mogul who criticized Xi's demands last month had his social media accounts deleted, and quickly became the target of criticism by commentators in state media.
RACHEL MARTIN, HOST:
And now a question - who would have the chutzpah to call on China's president to resign? That question seems to be weighing heavily on some members of China's security apparatus. They've been detaining and questioning people about the origins of an anonymous online letter criticizing President Xi Jinping. NPR's Anthony Kuhn reports from Beijing on the manhunt and its implications.
ANTHONY KUHN, BYLINE: New York-based activist and blogger Wen Yunchao insists he did not write this letter. No matter, his mother, father and younger brother disappeared apparently into police custody in southern China.
WEN YUNCHAO: (Foreign language spoken).
KUHN: "I assume that they took my family members away," he says by phone from New York, "in order to force me to cooperate with their investigation into the letter or even to get me to confess to being involved with it." The letter was published online earlier this month and calls on Xi Jinping to step down. Several editors and managers at a Chinese news website that posted the letter have since been detained.
(SOUNDBITE OF ARCHIVED RECORDING)
UNIDENTIFIED MAN: (Foreign language spoken).
KUHN: Animated propaganda videos, like this one, portray president Xi Jinping as a leader who is tough on corruption but close to ordinary citizens. The letter acknowledges that Xi's anti-graft drive has gotten good results. But it also argues that Xi has amassed too much power in his own hands and that this has undermined the Chinese state and its policies. Others have made similar criticisms without calling on Xi to resign.
WILLIAM NEE: It seems like there have been a massive amount of resources put into this case to investigate who wrote the letter, how it was disseminated and to stop people from talking about it overseas.
KUHN: William Nee is a Hong Kong-based researcher for Amnesty International. He argues that Chinese authorities could have just chosen to censor the article online. But by choosing to launch a manhunt for the author of the letter, Beijing has actually attracted extra attention.
NEE: From a human rights angle, it's absolutely egregious that people who are family members or overseas dissidents have done nothing but comment on the letter and the current affairs are being targeted. And this is really kind of reaching a new level in the crackdown on dissent in China.
KUHN: Authorities have also detained relatives of Germany-based journalist Zhang Ping in an apparent attempt to stop him from so much as commenting on the letter. Activist Wen Yunchao says police had previously told his family members to tell him not to criticize the Communist Party. But he says he was not prepared for his relatives' disappearance.
YUNCHAO: (Foreign language spoken).
KUHN: "Try as I might," he says, "I could never have imagined that they would use such barbaric, inhumane methods to handle this matter." Many, if not most people inside China don't know about the letter because domestic media haven't said a word about it. The conservative state-run tabloid, the Global Times, said in an English-language op-ed that authorities investigating the case will announce their findings in due time. And until then, people should not rush to conclusions. Anthony Kuhn, NPR News, Beijing. Transcript provided by NPR, Copyright NPR.