The U.S. arrested a Navy Department employee and his wife on spying-related charges after they allegedly sold restricted data on nuclear-powered submarines to an FBI agent posing as a foreign official.

Jonathan Toebbe, 42, and his wife Diana, 45, were ensnared in an investigation involving cryptocurrency payments, encrypted emails and a "dead drop” in West Virginia of a memory card hidden in a peanut butter sandwich, the Justice Department said in a statement on Sunday.

Jonathan Toebbe, a nuclear engineer assigned to the Naval Nuclear Propulsion Program, set the probe in motion by sending a package in April 2020 to a foreign government, with a sample of restricted data and an offer to sell them more, according to the statement.