Reuters could not determine the full scope of the federal investigation or whether it involved the same alleged problems with animal testing identified by employees in Reuters interviews. Musk has pushed hard to accelerate Neuralink’s progress, which depends heavily on animal testing, current and former employees said. Delcianna Winders, director of the Animal Law and Policy Institute at the Vermont Law and Graduate School, said it is “very unusual” for the USDA inspector general to investigate animal research facilities. In September, the company responded to employee concerns about its animal testing by holding a town hall to explain its processes. “We’re extremely careful,” he said, to make sure that testing is “confirmatory, not exploratory,” using animal testing as a last resort after trying other methods.