A Maryland-based Navy nuclear engineer and his wife have been arrested on charges of selling secret information about the design of nuclear power warships to someone they thought was a foreign power but was actually an undercover FBI agent.

The Justice Department claims Jonathan Toebbe, through his Pentagon-issued national security clearance, had access to restricted data about naval nuclear technology and used that access to send a package to a foreign government on April 1, 2020. After that, the affidavit alleged he began corresponding with someone he believed to be an agent of another country, but who was an undercover FBI agent. Court documents claim the Navy engineer agreed to sell this restricted data to the undercover agent for $10,000 in cryptocurrency.

Toebbe and his wife, Diana, then allegedly went to West Virginia, where the Navy engineer placed a memory card inside half a peanut butter sandwich, with his wife on the lookout. According to the Justice Department, the card contained restricted data about submarine nuclear reactors.

Based on the criminal complaint, the engineer at one point suspected a trap, but continued with more such “dead drops.”

“I am sorry to be so stubborn and untrusting, but I can not agree to go to a location of your choosing,” the engineer said, according to a criminal complaint. “I must consider the possibility that l am communicating with an adversary who has intercepted my first message and is attempting to expose me.”

Attorney General Merrick Garland said the complaint “charges a plot to transmit information relating to the design of our nuclear submarines to a foreign nation.”

“The work of the FBI, Department of Justice prosecutors, the Naval Criminal Investigative Service and the Department of Energy was critical in thwarting the plot charged in the complaint and taking this first step in bringing the perpetrators to justice,” Garland said.

— CBS News’ Catherine Herridge contributed to this report