NEW YORK (NYTIMES) - Agents from the Federal Bureau of Investigation (FBI) spent nearly two years tailing the professor, following him to work and to the grocery store and keeping his college-age son under surveillance.
They told the university where he held a tenured position that he was a Chinese operative, prompting the school to cooperate with its investigation and later fire him.
But the FBI was unable to find evidence of espionage, according to an agent's testimony in court.
Federal prosecutors pressed charges anyway, accusing Dr Hu Anming of concealing his ties with a university in Beijing and defrauding the government in connection with research funds he had received from Nasa. The trial ended in a hung jury.
One juror called the case ridiculous. In September, a judge acquitted the Chinese-born scientist on all counts.
"It was the darkest time of my life," Dr Hu said.
Universities in the United States once welcomed the best and brightest scientific talents from around the world.
But government officials have become increasingly suspicious that scientists such as Dr Hu are exploiting the openness of American institutions to steal sensitive taxpayer-funded research at the behest of the Chinese government.
It has had a chilling effect across campuses that scientists and university administrators say has slowed research and contributed to a flow of talent out of the US that may benefit Beijing.
In interviews with several scientists of Chinese descent working in American universities, a picture emerged of a community on edge.
Some described being humiliated by mandatory training on foreign interference that featured only examples of ethnic Chinese scientists, and unexplained delays for visa renewals.
They were all concerned that seemingly anything could provide an opening for federal investigators to come knocking.
A recent study conducted by the University of Arizona and the Committee of 100, an organisation of prominent Chinese Americans, surveyed scientists of both Chinese and non-Chinese descent working at academic institutions in the US on issues of race and ethnicity in science and research.
Around half of the Chinese scientists surveyed said they felt that they were under surveillance by the US government.
Some have blamed a law enforcement programme called the China Initiative.
The programme is aimed at preventing the Chinese government's theft of American trade secrets and other acts of espionage.
But scholars, scientists, civil rights groups and lawmakers have asked whether it has gone too far in targeting academics.