WASHINGTON — A Navy nuclear engineer with access to military secrets has been charged with trying to pass information about the design of U.S. nuclear-powered submarines to someone he thought was a representative of a foreign government but who turned out to be an undercover FBI agent, the Justice Department said Sunday.

In a criminal complaint detailing espionage-related charges against Jonathan Toebbe, the government said he sold information for nearly the past year to a contact he believed represented a foreign power. That country was not named in the court documents.

Toebbe, 42, was arrested Saturday in West Virginia along with his wife, Diana, 45, after he had placed a removable memory card at a prearranged “dead drop” in Jefferson County, according to the Justice Department.

It wasn’t clear whether either Toebbe had a lawyer. The Toebbes are from Annapolis, Maryland. The Navy declined to comment.

The FBI says the scheme began in April 2020 when Jonathan Toebbe sent a package of Navy documents to a foreign government and said he was interested in selling operations manuals, performance reports and other sensitive information.

Authorities say he also provided instructions for how to conduct the secretive relationship. The FBI’s legal office in the foreign country received the package, which had a return address of Pittsburgh, last December.

In June, the FBI says, the undercover agent sent $10,000 in cryptocurrency to Toebbe, describing it as a sign of good faith and trust.

The following week, FBI agents watched as the Toebbes arrived in West Virginia for the exchange, with Diana Toebbe appearing to serve as a lookout, according to the complaint.