Chinese postdocs in U.S. hit with a wave of prosecutions and deportations

From ScienceMag:

“I’ll be working on the final figures for the review paper tomorrow,” Yunqing Jian emailed her adviser. But the 33-year-old postdoc in the molecular plant-microbe interaction (MPMI) laboratory at the University of Michigan (UM), run by Libo Shan and her husband, Ping He, never got the chance. The next day, 3 June 2025, she was arrested by FBI and charged with improperly transporting biological materials in an alleged conspiracy involving her ex-boyfriend, Zunyong Liu, a former postdoc in the MPMI lab.

Jian would be the first in a cluster of Chinese postdocs at UM and Indiana University (IU) arrested over the next 5 months for actions the U.S. government claims posed an imminent threat to national security. The U.S. attorney in the Jian case, Jerome Gorgon, called the material the pair were accused of smuggling—a well-studied strain of a fungus, already found in the United States, that attacks wheat—a “potential agroterrorism weapon.”

The other cases triggered similar dire warnings from high-ranking federal officials. Then–Attorney General Pamela Bondi said Chengxuan Han, who shipped samples of Caenorhabditis elegans, a tiny worm used as a model organism by neurobiologists around the world, to UM, was “attempting to smuggle biological materials under the guise of research, [which] is a serious crime that threatens America’s national and agricultural security.” And after IU postdoc Youhuang Xiang was arrested for receiving a shipment of plasmids—circles of DNA often used to genetically engineer organisms—derived from Escherichia coli, a ubiquitous microbe, FBI Director Kash Patel warned that “if not properly controlled, [these] biological materials could inflict devastating disease to U.S. crops and cause significant financial loss to the U.S. economy.”

The UM and IU cases resulted in four convictions of Chinese postdocs. Six of the seven scientists charged were also deported, a step made easier by their status as foreign nationals on temporary visas. (Liu, the seventh, was already in China.) For these postdocs, deportation is essentially a permanent ban on returning to the U.S. and an end to their dream of contributing to the U.S. research enterprise.

The prosecutions have also disrupted the lives of the senior scientists who employed them. One, neurobiologist X.Z. “Shawn” Xu, has left Michigan and moved his lab to China. Shan and He, both U.S. citizens, were investigated before being cleared. And IU’s Roger Innes, a plant molecular biologist who supervised Xiang, has been locked out of his lab because of an ongoing federal investigation and, along with a colleague, blocked from exchanging research materials with outside collaborators.

The impact of the prosecutions has rippled across both campuses, with some scientists calling them racially biased and an overreaction to minor infractions. “It’s had a chilling effect on both faculty and students,” says cell biologist Dawen Cai, co-president of the University of Michigan Association of Chinese Professors.

The chair of Shan’s department, biologist Ken Cadigan, says some of his colleagues fear the worst. “Even if I’m a U.S. citizen, they can take that away and deport me if I make one small mistake,” he says he’s hearing in the hallways.

Elements of the prosecutions are reminiscent of the China Initiative, which the Department of Justice (DOJ) launched during President Donald Trump’s first term to root out economic espionage by the Chinese government. It led to the arrest of some two dozen senior Chinese-born scientists at U.S. institutions who were alleged to have failed to disclose their ties to Chinese entities. The government lost or dropped many of those cases, however, and in 2022 then-President Joe Biden officially ended the program after widespread complaints that it had unfairly targeted scientists of Chinese descent, most of whom were U.S. citizens.

A different demographic—Chinese postdocs on temporary visas—has become the latest target of DOJ investigations. And the Trump administration and Republican members of Congress have now singled out mislabeling of biological materials as a threat to national security as serious as economic espionage. In a letter to the UM president shortly after the June 2025 arrests of Jian and Han, the chairmen of three committees in the U.S. House of Representatives wrote: “Chinese researchers tied to the PRC [People’s Republic of China] defense research and industrial base have no business participating in U.S. taxpayer-funded research with clear national security implications—especially those related to dangerous biological materials.”

Prosecuting cases of alleged mishandling of biological materials is a big change for DOJ, says Michael German, former FBI special agent and national security expert. “That is typically not something the government cares very much about unless it involves a dangerous pathogen,” German says.

They are getting the clear message that the government doesn’t want them to be here.

• Roger Innes
• Indiana University Bloomington

Biological samples are an appealing target for prosecutors, German and lawyers for the defendants say, because laypeople assume all such material is potentially threatening. “In this particular case, we’re talking about plasmid DNA of E. coli bacteria,” Assistant U.S. Attorney Matthew Rinka said at Xiang’s 7 April plea and sentencing hearing. “In the next case, we may very well be talking about something that is harmful, such as anthrax or a strain of some fungus that has never been in the United States.”

Scientists and others familiar with the cases agree that the government needs to enforce existing rules on labeling and shipping biological materials. But prosecuting seemingly minor violations of those rules as felonies criminalizes the routine practice of sharing samples and resources with colleagues, they add. That crackdown is especially hard on foreign scientists, who are likely to request or bring materials from home because they don’t know what materials will be available in their new U.S. labs, Innes says.

Those from China are especially vulnerable, Innes notes, because of the heightened political and economic tensions between the two countries. “Even though it’s perfectly legal to ship or import something like plasmid DNA if you properly label the package,” Innes explains, Customs and Border Protection [CBP] “agents will probably confiscate it because they don’t trust any kind of biological material coming from China or another country of concern.”

Although federal criminal investigations involve a large team from multiple government agencies, the UM and IU cases drew heavily on the work of one person: FBI Special Agent Edward Nieh. Assigned to the Detroit field office of FBI’s counterintelligence division, Nieh played a role in all the arrests—and was directly involved in the cases of Jian and Han. Science has reconstructed his role by drawing on his affidavits to the court; FBI declined to make him available for an interview.

Jian became a target after her former lab mate Liu was stopped by CBP at the Detroit airport on 27 July 2024, when he arrived on a flight from Shanghai. Liu, a new assistant professor at Zhejiang University, a top-tier Chinese university, was taking a working vacation, according to David Duncan, Jian’s lawyer—visiting her and hoping to use the fluorescence microscope at MPMI to study samples of the wheat-blight fungus Fusarium graminearum (Fg) he had brought with him. “It was pretty clear this was a workaholic scientist who didn’t want to leave his work behind, and so he brought it with him in his suitcase,” Duncan says.

Liu was refused entry into the U.S. and immediately sent back to China, thus avoiding prosecution. But FBI confiscated his phone, which contained exchanges that implicated Jian. Among the information Nieh gleaned was that Jian hid undeclared research material in her shoe when she came to the U.S. in August 2022 to work with Shan and He, who were then at Texas A&M University before moving to UM a year later.

On 5 February 2025, Nieh interviewed Jian and then took her phone, on which FBI found a year-old conversation in which Jian, now at UM, asked another scientist at Zhejiang to send her some plasmids. That material had been seized and destroyed by U.S. customs officials.

Facing such evidence, Jian agreed to plead guilty to smuggling biological material and making false statements during her interrogation. On 12 November 2025, after 5 months in jail, she was sentenced to time served and, within a few days, deported.

“Dr. Jian acted illegally,” Duncan conceded during her sentencing hearing. “But her motive … was to speed up her research and help her boyfriend speed up his research,” he added. “Throughout their career, their goal has been to protect crops from these fungi, not spread it.”

Before Jian was sentenced, Duncan solicited a letter from Innes in which he explained that the material Liu had brought with him posed no threat to Michigan farmers or the public, noting it is already present in the state. “Notably, this strain was originally collected from a grain elevator in Michigan in 1996 … and is ubiquitous in the state, which is why farmers spend so much money trying to control it,” Innes wrote in his letter, which became part of the public record.

Jian’s conviction accelerated FBI’s investigation of Xiang. One week after she was sentenced, FBI’s Detroit office notified the Indianapolis office it had come across “shipments from the PRC to individuals at IU whose research focused on pathogen resistance and susceptibility in wheat, the same as that of [Jian and Liu].” In particular, FBI discovered that Xiang had received samples of plasmid DNA in March 2024 from the Chinese Academy of Sciences as part of a shipment from the “Guangzhou Sci Tech Innovation Trading” company labeled as “women’s underwear.”

Innes believes his letter in support of Jian and Liu was what drew scrutiny to his postdoc, and Duncan agrees. “Why would Innes be on the Michigan FBI’s radar, except for that letter?” says Duncan, who has decades of experience defending defendants in federal court. “There’s no other connection.”

[The prosecutions] had a chilling effect on both faculty and students.

• Dawen Cai
• University of Michigan Association of Chinese Professors

Nieh says in the charging document he learned that Xiang would be flying into Chicago on 23 November 2025 after a 2-month stint at a U.K. agricultural research station outside London, whose scientists collaborate with Innes. U.S. law enforcement officials interrogated Xiang upon his arrival and, after questioning him, arrested and charged him with making false statements.

The U.S. government immediately revoked Xiang’s immigrant visa, meaning he was in the country illegally. Posting bail would have likely triggered his rearrest and reincarceration by the Department of Homeland Security for an indefinite period. So Xiang declined to post bail and endured a 4-month odyssey through five U.S. jails and detention facilities while his lawyers negotiated with DOJ officials. On 7 April, Xiang pleaded guilty to one count of smuggling plasmid DNA and was sentenced to time served. He served another 11 days in an Indiana county jail before being deported back to China.

Rinka said he hoped the conviction would send a message to all academic scientists. “Once again, it is not for the faculty of any higher educational institution to determine what may or may not be brought to the United States at their whim and fancy,” Rinka argued.

Nieh’s pursuit of undeclared samples also ensnared Han, whom her lawyer describes as a “nerdy, kind, and polite academic.”

Han, who was close to completing her doctoral degree in neurophysiology from the Huazhong University of Science and Technology (HUST), was set to begin a 1-year stint at UM as a visiting scientist in Shawn Xu’s laboratory in August 2025. In the year before starting work there, she had shipped at least five packages containing C. elegans and plasmid DNA to three Chinese postdocs in the lab without proper labeling, according to records Nieh obtained from CBP, which had confiscated the packages.

In March 2025, CBP officers contacted one intended recipient, postdoc Xu Bai. Although Xu declined to speak or meet with them, on 8 June Nieh interviewed two other postdocs from the lab, Fengfan Zhang and Zhiyong Zhang, as they were waiting at the Detroit airport to pick up Han, their future colleague. Han was detained as soon as her plane landed and, after a lengthy interrogation, taken into custody and charged with smuggling, conspiracy, and making false statements.

Instead of collecting more data for her dissertation on how organisms process and respond to sensory cues, Han found herself behind bars. “Her career has been irreparably damaged,” her lawyer, Benton Martin, told U.S. District Judge Matthew Leitman on 10 September 2025 before he found her guilty of smuggling material. “She has lost her prestigious research opportunity at the University of Michigan … and in all likelihood the chance to become a professor in China, which requires international research experience.” Han was sentenced to the 3 months she had already served in jail and then deported.

In press statements about the June 2025 arrests of Jian and Han, DOJ officials suggested they were part of a concerted effort by the Chinese government to infiltrate U.S. universities. Within days, the three House committee chairs had amplified that message in a stern, 10-page letter to interim UM President Domenico Grasso. They called for a “full review of all grants to MPMI” for possible violations of any federal statutes or regulations. The chairmen sent a nearly identical letter to the heads of the National Institutes of Health (NIH) and the National Science Foundation (NSF), which have funded Shan and He.

Science has been unable to determine the status or outcome of those investigations. A spokesperson for the House committees said, “We don’t have any updates for you,” and spokespeople for NIH and NSF declined comment. A UM spokesperson also declined comment, although Science has learned that the House letter triggered the university investigation of Jian’s mentors, Shan and He.

The three postdocs in Shawn Xu’s lab were fired shortly after they declined to meet with UM lawyers on 29 September 2025. “They said they had been told by their academic adviser [in China] not to talk to anyone,” says attorney John Minock, who represented Xu Bai. “And when I asked them how responsible for their academic careers that person was, they laughed and said, ‘100%.’ So, it was essentially an order.”

Their J-1 visas were revoked soon after they were fired, which meant they were in the country illegally and subject to arrest and deportation. Nieh told the court he learned the three men had booked a flight to China on 16 October 2025 from John F. Kennedy International Airport and apprehended them there.

But on 4 February, after nearly 4 months in jail, they were released and allowed to fly home. According to their lawyers and several media reports, the Chinese embassy had intervened and struck a deal with the Trump administration to make the charges go away. “We never knew why, or who initiated it,” Minock says.

The U.S. government still gets credit “for arresting and deporting the scientists,” Minock notes, which he says is “an important goal for this administration.” But the episode was costly to U.S. taxpayers. “They had been confined for more than 3 months,” Minock says, “and the government probably spent $200,000 or $300,000 over the course of the prosecution before the cases were dropped.”

German argues the prosecutions have other costs as well. “Amplifying these cases into an alleged threat to national security reinforces the stereotype and the impression that there is this concerted activity, especially if you’re focusing on one particular racial or ethnic group or one particular nation.”

FBI and DOJ officials say they are simply doing their jobs. “The FBI remains resolutely committed to collaborating with our law enforcement partners to protect the residents of Michigan and defend the United States against such grave threats,” said Cheyvoryea Gibson, special agent in charge of the FBI Detroit field office, after Jian was arrested.

Although never charged with a crime, the mentors of these postdocs have also suffered. Shan says Jian’s departure has forced her lab to delay publishing important findings. Shan and He also face lengthy questioning at the airport every time they return from a scientific meeting abroad.

For Shawn Xu, the pall of suspicion hanging over his UM lab was dark enough for him to relocate to China “rather than wait for the noose to tighten,” according to Minock. He is reportedly now working at HUST and his students and postdocs still at UM have received short-term support from the university as they scramble to find other advisers.

Innes, who last year was elected to the National Academy of Sciences, has been outspoken in defense of his colleagues of Chinese ancestry, who he says are lying low. But Innes has also paid a price, including restrictions on his research activities and the cancellation of a long-running project.

The day after Xiang was sentenced, Innes received an email from the head of IU’s public safety office ordering him and a departmental colleague “to cease all importing and exporting activities in connection with your research, effective immediately and until further notice.” The office head acknowledged the unusual directive was “inconvenient and less than ideal during the academic year,” but said it was necessary so IU “could respond to inquiries” from federal regulators “regarding IU’s policies and procedures in connection with the import and export of certain biological materials.”

Innes also faces an ongoing government investigation. In December 2025, FBI agents searched his lab and office in the presence of IU lawyers and confiscated a notebook containing seeds of Arabidopsis thaliana, the model organism he uses to study Fusarium head blight.

“There was some Chinese writing in the notebook, which is probably why they took it,” says Innes, who received the seed packet in 2018 from a colleague in China and never opened it.

On 3 February, Innes received a letter from the U.S. Department of Agriculture (USDA) saying his lab “is in compliance” with government regulations. But the next month, USDA canceled a long-running collaboration between its scientists and Innes’s lab. Ironically, the work involves finding better ways of helping plants build resistance against the Fusarium fungus. “And now that experiment will never be finished,” Innes notes.

And 3 weeks after Xiang was sentenced, USDA told Innes it had sent the letter “in error.” On 7 May, the university locked him out of his lab. “We have been notified by the US Department of Agriculture that they will be engaging in activity in a laboratory associated with the biology department,” wrote Russell Mumper, vice president for research, in an email obtained by Science.

USDA declined a request for comment.

Many congressional Republicans have urged the Trump administration to resurrect the China Initiative, seeing a continuing threat. In the wake of these convictions and deportations, those affected wonder whether DOJ has revived it in a new form. “Yeah, it seems so,” says Duncan, who represented Jian. “And postdocs are easier targets than the more senior scientists, most of whom are U.S. citizens.”

Anecdotal evidence suggests the prosecutions are causing more Chinese grad students and postdocs to question whether they want to come to the U.S. to further their scientific careers. “I’ve heard from [my UM] colleagues that top candidates are declining offers and choosing to go instead to the U.K. or Europe or Singapore,” Cai says.

There are no numbers to support the anecdotes, as UM does not break out student totals by country and posts no data on postdocs. And Cai says his colleagues feel UM “is a safer place” than most U.S. universities at the moment because of its continued vocal support for international collaborations.

But Innes worries about the broader environment. “Most Chinese scientists came to the U.S. with the hope of staying for their careers,” he says. “But now they are getting the clear message that the government doesn’t want them to be here.”

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