World Health Organization investigators working in China say they’ve found absolutely no evidence to support the theory that the coronavirus originated in a Wuhan laboratory—and they think it’s such an outlandish theory that they’re going to bring an end to their research into it. Peter Ben Embarek, an animal-diseases expert, announced the decision during a press conference following a long-awaited visit by WHO experts to the city of Wuhan, where the virus was first identified. Embarek said it’s “extremely unlikely” that the virus came from a lab, and that the most likely cause of the initial outbreak was the virus jumping from an undetermined “intermediary host species” to humans. The lab-origin theory was fueled by the U.S. State Department under President Donald Trump, which claimed last month that it had obtained intelligence that researchers at the lab became sick with COVID-19-like symptoms in autumn 2019.