The arrests are related to biological research and specimens that China was paying for. The researchers failed to disclose the connections to the US government and/or tried to smuggle specimens to China. Likely there is no connection to the Corona virus but that won't stop people from trying to make the connection. And right now, we don't really know exactly what the professor was doing. One of them was likely just cancer research, and another was more computer science and robotics. Almost certainly unrelated. The third was unclear from the NPR article.