A former CIA employee who was arrested Monday is reportedly suspected of betraying dozens of CIA assets in China and possibly causing the deaths or imprisonments of about 20 of them.
The Department of Justice says Jerry Chun Shing Lee was arrested after landing at JFK Airport in New York. Back in 2012, authorities found two books in Lee's possession that had the names and phone numbers of assets and undercover CIA employees, locations of undercover facilities and notes about secret operations, among other information.
The DOJ says at the time of those searches, Lee and his family were in the process of moving back to the U.S. NBC News reports that same year, the FBI convinced Lee to come back to the country with a fake job offer. They report no charges were filed.
The DOJ says he's being charged with illegally possessing national defense information and could face 10 years in prison.
But several outlets report Lee is tied to much more than just those two notebooks: Sources say he helped the Chinese government identify assets in a systematic effort to cripple U.S. spying in the country. That operation started in 2010, and resulted in the deaths or imprisonment of 18 to 20 CIA assets, according to The New York Times.
Lee started working at the CIA in 1994. During his time there, the DOJ says he had a top-secret security clearance and access to highly sensitive information. His clearance was canceled when he stopped working for the U.S. government in 2007.
Lee is a naturalized U.S. citizen, but he was living in Hong Kong at the time of his arrest. Officials tell NBC News it's unlikely he'll be charged with espionage.