The first controversy to catch Zhu’s eye was a scandal over tainted milk powder that killed six babies and sickened tens of thousands more. He joined chat groups and get-togethers and slowly slipped into dissident circles.

After President Xi Jinping — China’s most authoritarian leader in decades — came to power, Zhu’s views brought him more and more trouble. In 2014, he was detained for a month after donning a black shirt and a white flower at a Wuhan plaza in remembrance of the Tiananmen Square crackdown, estranging him from his teenage son.

But when a mysterious respiratory illness began spreading through Wuhan early last year, Zhu’s deep-seated skepticism toward the government suddenly proved prescient. After seeing rumors of the disease in late December 2019, Zhu began warning friends and family. Many brushed him off as an obstinate gadfly, but his wife and son stayed home, saving them from outings that would soon sicken relatives.