This is the second case revealed in about a week involving a Chinese academic smuggling biological material into the U.S. A criminal complaint filed Monday alleges Chengxuan Han sent four packages in the last several months.

Two Chinese researchers were charged with smuggling a biological pathogen that they planned to study at a University of Michigan lab, a complaint says.

Federal authorities arrested a Chinese researcher connected to the University of Michigan, marking the third such case in two weeks involving the alleged smuggling of biological materials from China.