Surely the FBI should be held to account when they make mistakes or behave unfairly, but it seems absurd that they shouldn't consider connections to China when looking for Chinese espionage.
For example, Walter Liew stealing the titanium dioxide formula (with help from paid off non-Chinese), or the engineering student in Chicago sending off recruiting profiles...all Chinese or Taiwanese.
I am extremely worried by China's panopticism, especially in Xinjiang[1]. But violating the rights of Chinese students so egregiously that you're unable to secure a conviction because your evidence is "fruit of the poisonous tree"[2] harms American interests by handing a propaganda victory to the PRC.
The FBI needs to ensure they follow the law when they investigate espionage so that offenders can be changed and convicted.
[1] https://www.nytimes.com/interactive/2019/04/04/world/asia/xi...
[2] https://en.wikipedia.org/wiki/Fruit_of_the_poisonous_tree
The FBI may very well have been overzealous here (especially considering the history of the organization), but I think we'd need to look at the facts of each case in detail, rather than only the charge and conviction statistics by nationality. The case with the Temple professor appears to have resulted from a misinterpreted email.
In general, you shouldn't be taking cases to trial you can't win, whether if it's due to evidence being thrown out or evidence not being present in the first place.