Chinese real estate tycoon Ren Zhiqiang disappeared on Thursday, shortly after penning an online article strongly critical of the Chinese government’s response to the coronavirus epidemic.

Some of Ren’s friends and admirers believe he was kidnapped by the Chinese Communist Party and is being held incommunicado for the “crime” of speaking out against the Party and China’s dictator Xi Jinping.

Ren’s article was entitled “The Lives of the People Are Ruined By the Virus and a Seriously Sick System.” It did not mention Xi by name, but it criticized many of the decisions he has made, particularly allowing a now-infamous mass banquet to proceed in the city of Wuhan in January while the coronavirus outbreak was erupting in that city.

“The emperor is holding up a piece of cloth, trying to cover up the fact that he is wearing no clothes at all, although his ambition to be a strong leader is naked enough,” Ren wrote in a passage that was rather obviously aimed at Xi without using his name.

Ren said he saw “not an emperor standing there exhibiting his ‘new clothes,’ but a clown stripped naked who insisted on continuing being emperor,” according to one translation of his online essay.

“The covert propaganda around the decisions made during the Wuhan coronavirus epidemic will only deceive those who are willing to be deceived,” he charged, another fairly obvious reference to orders given by Xi. He said the Chinese government made the epidemic much worse by suppressing discussion and early warnings.

The property tycoon has long been known by the nickname “Ren the Big Cannon” for his outspoken criticism of the Chinese government, particularly its efforts to control the property market and to use Chinese media for propaganda purposes. His account on China’s microblogging platform Weibo had 37 million followers at its peak, but was suspended and then deleted in 2016 after he made comments that displeased the Communist Party.

Ren made few public appearances since that time and is thought to have been under constant surveillance, but he continued making dissident comments until last week when his essay on the coronavirus was followed by his abrupt disappearance.

His absence was publicly noted by several influential Chinese businessmen and academics. International media organizations attempted to contact him over the weekend, without success. The New York Times said on Saturday the Beijing police did not respond to a request for comment about Ren’s whereabouts. China’s State Council Information Office also did not respond to request for information, according to the UK Daily Mail.

“A citizen can’t just disappear, we need to know if he’s been taken by any department and where. His family and friends should know,” said Renmin University history professor Zhang Ming.

“Ren Zhiqiang is a public figure and his disappearance is widely known. The institutions responsible for this need to give a reasonable and legal explanation as soon as possible,” said businesswoman Wang Ying. She said she and other friends of Ren are “extremely anxious” about his situation.