> About a dozen F.B.I. agents, some with guns drawn, stormed Dr. Xi’s home in the Philadelphia suburbs in May, searching his house just after dawn...
How did they see the emails? Was it mass surveillance or did someone complain to the FBI?
Arrests based on the mass surveillance of millions of people is far scarier than arrests based on sincere accusations from concerned citizens.
The most likely answer if they got emails from whoever they were sent or forwarded to.
Chinese spies looking for this information would, presumably, pose as experts or students and get involved in academic discussions at conferences and email chains/listseves.
So hypothetically the FBI could bust a real spy, then see emails from Dr. Xi sending technical information and they suspect the worst.
The FBI could have even infiltrated these groups themselves directly, which doesn't require a warrant or any oversight.
One other way I just thought of is that public school employees, like Temple, don't own their work email. A regular person can use FOIA to get professors emails. I wonder if the FBI is allowed to use FOIA.
At least some law enforcement has a track record of acquiring evidence one way and, once they know what the resulting evidence should be, reconstructing it in a court-admissable way.