It was sometime before 7am on 21 May 2015 when Xiaoxing Xi, a physics professor at Temple University in Philadelphia, was woken by people pounding on his front door. Still not fully dressed, he opened the door to be confronted by about 12 armed FBI agents.
The agents burst into Xi’s house, running about, shouting “FBI, FBI”. They pointed their guns at his wife and two daughters and ordered them to walk out of their bedrooms with their hands raised. Xi was handcuffed and arrested in front of his family.