A Chinese medical researcher was arrested in Boston earlier this month on suspicion of trying to take stolen biological samples back to China, according to an affidavit by an FBI agent. According to the agent’s testimony, published with redactions on Universal Hub, a community news and information site for the Boston area, Zheng Zaosong, 29, was questioned at Logan International Airport on December 9. FBI Special Agent Kara Spice said 21 wrapped vials containing a “brown liquid” that appeared to be “biological material” were found in a sock during an inspection of his checked baggage. He is now under investigation for attempting to bring undeclared biological samples back to China and making “false, fictitious and fraudulent statements” to US customs. Gene-edited baby scandal: where is scientist He Jiankui? Zheng, a doctoral student at Sun Yat-sen University in Guangzhou, had been doing research at the Boston-based Beth Israel Hospital and was due to catch a flight to Beijing. According to the affidavit, Zheng had been asked multiple times whether he had been travelling with any biological items or research material in his baggage and denied it each time. He was then escorted to a baggage room, where customs officers showed him the vials found in his checked luggage. He was asked why he did not declare the vials and replied that they were not important and had been given to him by a friend named Zhang Tao. The affidavit said Zheng had failed to explain why he had concealed these vials in a sock in his baggage. The document says Zheng was later taken to an interview room and confessed that he had stolen eight vials from the research lab at Beth Israel Hospital and he had replicated 11 vials from Zhang Tao’s research. The affidavit added that Zheng said he had planned to take these vials to Sun Yat-Sen Memorial Hospital for further analysis and hoped to publish a paper under his own name if the research proved successful. The biological samples are currently being examined and their contents remain unknown. A laptop owned by another Chinese national was also found in Zheng’s baggage and the FBI concluded it contained research material after an initial inspection. Zheng explained that he was taking it to China for his friend who “could not fit it in his luggage”. The Universal Hub reported that a federal judge had set bail at US$100,000 at a hearing on Wednesday but revoked it later. A spokesperson for Sun Yat-sen University did not respond to requests for comment on Sunday. According to the official website of Sun Yat-sen Memorial Hospital, an affiliate of the university, a student named Zheng Zaosong was among the winners of the “excellent student scholarship” awarded in 2018. The case took place at a time when tensions and mistrust are building up between China and the US over scientific exchanges. The US has already enhanced scrutiny and tightened visas for Chinese researchers and doctoral students in certain fields due to concerns about intellectual property theft. The New York Times reported last month that the National Institutes of Health and the FBI had started a major effort to root out scientists who are stealing biomedical research for other countries from institutions across the US. Chinese scientist pleads guilty to stealing trade secrets Almost all of the incidents they uncovered and that are under investigation involve scientists of Chinese descent, including naturalised American citizens, acting on behalf of China, the report said. It cited government officials and university administrators who said that some of those under investigation were suspected of setting up labs in China that secretly duplicated American research. China has been asking the US to treat Chinese scientists and researchers in a fair manner. A translated report about Zhang’s case was published on the Chinese social media outlet WeChat, prompting questions about his behaviour from web users. “Even if the samples can be smuggled outside the US border, it will be illegal to take undeclared biological materials into China,” one commented. “You are making life very difficult for every future Chinese student [in the US],” another commented. For more insights into China tech, sign up for our tech newsletters , subscribe to our award-winning Inside China Tech podcast , and download the comprehensive 2019 China Internet Report . Also roam China Tech City , an award-winning interactive digital map at our sister site Abacus .