A routine building inspection in Reedley led to a discovery that has since raised national security and public health concerns across the US.
A local inspector entered what appeared to be a vacant warehouse in 2023 after noticing a foul smell and found an unlicensed and illegally operating laboratory containing hundreds of vials labelled as containing pathogens such as COVID-19, HIV and Ebola.
Investigators also discovered around 1,000 laboratory mice, along with makeshift equipment and biological materials stored in unsafe conditions.
Officials later described the site as an illegal operation lacking basic safety protocols.
The warehouse was linked to Jia Bei Zhu, a Chinese national accused by US prosecutors of running a fraudulent COVID-19 testing scheme.
Authorities arrested Ori Solomon, an Israeli national, in connection with a related probe after discovering similar lab equipment and unknown biological substances in a Las Vegas property.
Law enforcement agencies have flagged concerns about the potential existence of additional undiscovered facilities.
Local officials in California have criticised the initial federal response, citing regulatory gaps and concerns about oversight and response.
