WASHINGTON (Reuters) —  A former U.S. Navy nuclear engineer and his wife on Tuesday faced their first court hearing on charges they attempted to sell secrets about nuclear submarines to a foreign power in exchange for cryptocurrency.

Wearing orange prison jumpsuits, they briefly appeared at a federal courthouse in Martinsburg, West Virginia, for a formal reading of the criminal charges against them. They have not yet been asked to enter a plea to the charges.

Jonathan Toebbe and his wife, Diana, were arrested on Saturday in Jefferson County, West Virginia, following a yearlong sting operation by undercover FBI agents, the Justice Department said in a statement.

Toebbe, 42, a nuclear engineer with top-secret security clearance, is accused of sending Navy documents to an unnamed foreign entity in 2020, along with instructions for how to obtain additional information.

The Toebbes did not speak other than to briefly answer the judge’s questions, indicating they understood their rights.

The Justice Department did not name the country involved.

U.S. Magistrate Judge Robert Trumble scheduled a court hearing for Friday on the Justice Department’s request that the Toebbes be jailed while they await trial.

The Toebbes will remain in jail while they await Friday’s hearing.

No lawyer was present for the couple at Tuesday’s initial 15-minute court appearance. The judge told them they qualify for court-appointed legal counsel.

Toebbe, with the aid of his 45-year-old wife, allegedly sold secrets to an undercover FBI agent posing as a foreign official over the course of several months, the Justice Department said.

At one point, Toebbe hid a digital memory card containing documents about submarine nuclear reactors in half a peanut butter sandwich at a “dead drop” location in West Virginia while his wife acted as lookout, the Justice Department said.

The memory card contained “militarily sensitive design elements, operating parameters and performance characteristics of Virginia-class submarine reactors,” according to a federal court affidavit.

Another memory card was concealed in a chewing gum package, the Justice Department said.

Toebbe received separate cryptocurrency payments totaling $100,000, according to the Justice Department.

Officials said Toebbe and his wife, who are from Annapolis, Maryland, were arrested after placing another memory card at a drop site in West Virginia. They were charged with conspiracy and “communication of restricted data,” according to a criminal complaint.