Washington (CNN) Edward Peng, a naturalized US citizen living in California, is being charged with spying for China's Ministry of State Security, the Justice Department announced Monday.

Peng is alleged to have couriered thousands of dollars of cash through a series of dead drops to a double agent working for the US, and to have picked up classified information provided by the agent and delivered it to China, according to a court-filed affidavit. The exchanges occurred between June 2015 and July 2018, according to the filing.

The classified information, according to the more than 20-page FBI affidavit, was provided by the US government to a confidential human source who acted as a double agent. "At all times, the government carefully selected the classified information for the Source and were aware of the materials that the Source passed," the documents said.

The Justice Department released FBI surveillance video they say is of Peng leaving an envelope with $20,000 in a Georgia hotel room for the source and then returning two hours later to the same room and picking up an SD card with information left by the double agent. A couple of days later, the FBI says, Peng's spouse dropped him off at the airport in San Francisco where he boarded a flight for Beijing.

Peng became a US citizen in 2012, according to the FBI affidavit. He is believed to be working as a "tour and sight-seeing operator in the San Francisco area for Chinese visitors and students," according to the court documents. It was not immediately apparent if Peng had an attorney who could be reached for comment.

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