Yunqing Jian, 33, and Zunyong Liu, 34, were charged with conspiracy to commit offence or to defraud the US, smuggling goods into the country, false statements and visa fraud for bringing in the fungus Fusarium graminearum from China, according to the US Attorney’s Office for the Eastern District of Michigan.

“The Department of Justice has no higher mission than keeping the American people safe and protecting our nation from hostile foreign actors who would do us harm,” Attorney General Pam Bondi said.

Fusarium graminearum is described as “a potential agroterrorism weapon” that can cause disease in certain plants like wheat, corn, rice and barley, and is “responsible for billions of dollars in economic loss worldwide each year,” an FBI affidavit in support of the complaint says.

“The toxins produced by Fusarium graminearum cause vomiting, liver damage, and reproductive defects in livestock and humans,” the complaint states.

The 25-page criminal complaint does not allege that the defendants – who investigators say were in a relationship – had any plans to spread the fungus beyond the University of Michigan laboratory.

But it says Liu was aware of the restrictions on the material and deliberately hid it in a wad of tissues in his backpack.

Donell Harvin, former chief of homeland security for the District of Columbia, told CNN that a pathogen such as Fusarium is extremely dangerous.

“It doesn’t matter whether the person had good intentions,” he said. “If there’s some type of mistake, or mishap, or release, that could have catastrophic consequences.”

The charges come as the Trump administration is looking to revoke visas for Chinese students, especially those with alleged “connections to the Chinese Communist Party or studying in critical fields,” US Secretary of State Marco Rubio said last week.

FBI Director Kash Patel said in a post on X that the case is “a sobering reminder that the CCP (Chinese Communist Party) is working around the clock to deploy operatives and researchers to infiltrate American institutions and target our food supply, which would have grave consequences.”

The affidavit doesn’t specify what Jian and Liu’s intentions were in studying the fungus.

Jian, who was arrested by the FBI, remains in custody.

On Thursday, her detention hearing was adjourned until next week to allow time for a new defence lawyer to get up to speed.

Chinese Foreign Ministry spokesperson Lin Jian said during a news conference on Wednesday that he wasn’t familiar with the case, but said the government “always asks Chinese nationals overseas to strictly observe local laws and regulations, and protects their legitimate and lawful rights and interests in accordance with the law.”