It was an embarrassing acknowledgment that prosecutors and F.B.I. agents did not understand — and did not do enough to learn — the science at the heart of the case before bringing charges that jeopardized Dr. Xi’s career and left the impression that he was spying for China.

“I don’t expect them to understand everything I do,” Dr. Xi, 57, said in a telephone interview. “But the fact that they don’t consult with experts and then charge me? Put my family through all this? Damage my reputation? They shouldn’t do this. This is not a joke. This is not a game.”

Sorry, dude! Hey, we're not scientists, ya know? Xi Xiaoxing, we'd like you to meet |Wen Ho Li|.

Much the same with me last week flying to New York with a portable galvanostat, though the hair is gray not blond. They didn't even swab it and run that through their GC – mass spec.