An accidental discovery in rural California raised biosecurity fears

On a December day in 2022, Jesalyn Harper went to a vacant warehouse to check out some suspicious parking. She was the only full-time code-enforcement officer in the town of Reedley, California, and while she was there, she noticed a green garden hose sticking out of a wall—a violation she ought to investigate. To her surprise, when she was let inside, she encountered three women in lab coats saying they were Chinese. As Ms Harper entered the building she discovered “Biohazard” signs; vials labelled in a mix of English, Mandarin and some kind of cipher; and hundreds of caged white mice.