The findings support what scientists have been saying for months.
34-year-old Li Wenliang tried to warn the public about COVID-19 but was silenced by police for spreading rumors, eventually dying from the virus himself.
Health workers with no infection-control training or protective gear dealt with 200 Americans evacuated from Wuhan after the initial coronavirus outbreak.
The coronavirus has killed more than 2 million people worldwide, including more than 414,000 in the United States.
The politically sensitive investigation comes amid uncertainty about whether Beijing might try to prevent embarrassing discoveries.
China has reported no new domestically transmitted cases since early August, but it remains on high alert.
Tucker Carlson did not respond well when Facebook and Instagram said the Fox News host’s interview contained false information about the coronavirus.
The comedian disguised himself as a bluegrass artist and led some members of the crowd to sing about injecting liberals with the "Wuhan flu."
The Chinese city, which reported the world’s first COVID-19 cases in December, was reportedly spurred to act after the discovery of a new coronavirus cluster.
The Office of the DNI said it was still examining an as-yet-unproven theory that the outbreak may have resulted from "an accident at a laboratory in Wuhan.”