WASHINGTON — 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.

The package’s contents were obtained in December by the Federal Bureau of Investigation’s attache in the foreign country, according to the government’s criminal complaint. It didn’t identify the country.

Toebbe had access to information on naval nuclear propulsion, including militarily sensitive design elements, operating parameters and performance characteristics of reactors for nuclear powered warships, according to DOJ.