A married pair of scientists pleaded guilty to taking confidential data from a Pfizer lab where she worked and sending it to China where her husband was trying to develop a cancer vaccine.

Federal prosecutors say the scheme came unwound after the husband, Chenyan Wu, was caught trying to smuggle five suitcases filled with toxic chemicals into the United States after shutting his lab down near Shanghai and relocating it to the U.S.

“These are serious computer fraud and smuggling crimes,” said Randy Grossman, the U.S. attorney for the southern district of California. “One defendant failed to protect her employer’s confidential and important research, and instead used it to her and her husband’s advantage. Compounding the harm, the other defendant put travelers in harm’s way by illegally transporting his laboratory’s hazardous chemicals back to the United States.”

Wu pleaded guilty to smuggling goods and faces up to 20 years in prison when he is sentenced. Chen admitted to computer fraud and faces a year in prison.

Wu, 58, had once worked for Pfizer PFE, +3.17% in a lab in the United Kingdom, but left in 2010, according to court documents. He then relocated to China to start his own lab, TheraMab, which focused on mRNA vaccine research.

At the same time, his wife, Lianchun Chen, 51, began working for Pfizer at a lab near San Diego. Prosecutors say over the next several years, she sent copies of Pfizer mRNA research and sent it to her husband in China.

Messenger RNA, or mRNA, is the core technology used by Pfizer’s blockbuster COVID-19 vaccine, which it developed in partnership with Germany’s BioNTech BNTX, -2.51%. The Pfizer-BioNTech vaccine was the first mRNA product authorized and approved by the Food and Drug Administration. Pfizer expects to generate $32 billion from the vaccine in 2022. Researchers have also been working on targeting cancer with the technology.

Cases involving the theft of pharmaceutical trade secrets have become increasingly commonplace in recent years. The former director of the immune oncology division at Merck MRK, +1.32% was charged in January 2021 with stealing proprietary research. Last July, a husband-wife pair of researchers for Roche Holding’s Genentech ROG, +0.88% pleaded guilty to sending trade secrets to a startup overseas. 

In February, Pfizer filed a lawsuit against two former researchers they accused of taking confidential information to start their own lab. The researchers’ company later countersued Pfizer claiming the pharma giant was simply seeking to smear the reputation of a competitor.

A message sent to representatives of Pfizer wasn’t immediately returned.

Wu’s attorney, Jeremy Warren, said his client admitted he had made a mistake.

“Dr. Wu is an American citizen and a hard-working scientist looking to help people. He has never been in trouble before in his life and regrets what he has done,” Warren said. 

Chen’s attorney didn’t immediately respond to a message seeking comment.

In 2021, Wu — faced with a stoppage in funding for his lab from the Chinese government — decided to close it and relocate to the United States.

He then packed up the contents of his lab in five suitcases and flew back to the U.S. on a Delta flight through Seattle-Tacoma International Airport, where he planned to get a connection to San Diego where his wife lived.

Prosecutors say Wu failed to declare that he was carrying any chemicals or commercial materials on his custom’s form, but when his bags were searched in Seattle, agents found nearly 1,000 vials of chemicals. While most were commonplace lab chemicals, some were marked as dangerous and fatal if inhaled. The discovery prompted authorities to call a Hazmat team into the airport, according to court documents..

According to court documents, when questioned about the vials, Chen said China had onerous rules about transporting such materials, so he chose to “take a gamble to be honest.”

At that point, investigators had already begun looking into Wu after finding a Powerpoint presentation from his lab on the phone of a defendant who had pleaded guilty to violating export controls.