Chinese law professor Xu Zhangrun recently posted a scathing review of the way president Xi Jinping and the Chinese Communist Party have handled the coronavirus outbreak.

"They all blithely stood by as the crucial window of opportunity to deal with the outbreak of the infection snapped shut in their faces," he wrote, suggesting that government censorship of information about the coronavirus hampered China's ability to control its spread.

Xu, who teaches at Beijing's Tsinghua University, added: "The cause of all of this lies with The Axlerod [that is, Xi Jinping] and the cabal that surrounds him."

The essay, published online February 10, was immediately taken down. Xu was placed under house arrest, cut off from the internet, and scrubbed from all social media sites, The Guardian reported.

His critique came three days after Wuhan doctor Li Wenliang died of the coronavirus. Li had sent a message to a group of medical school alumni, warning them about a mysterious new illness. But local police reprimanded and silenced him.

In addition to Li and Xu, at least three citizen journalists have disappeared or were arrested after sharing information about the outbreak on social media.

Here's what we know about all five of them.