WASHINGTON — The Maryland couple charged in a plot to sell sensitive U.S. submarine secrets to a foreign government will remain behind bars for now, a judge said Tuesday in granting a detention request from prosecutors.

Jonathan and Diana Toebbe each made brief appearances in federal court in Martinsburg, West Virginia. Magistrate Judge Robert Trumble ordered them to remain detained pending a detention hearing on Friday at which more extensive arguments are expected to be made.

The couple answered perfunctory questions from a judge, but no substantive information about the case was revealed.

The Toebbes were arrested in West Virginia over the weekend. Jonathan Toebbe, a Navy nuclear engineer, is accused of passing information about American submarines to someone he thought was a representative of a foreign government but who was actually an undercover FBI agent.

The authorities say Diana Toebbe sometimes accompanied her husband to pre-arranged "dead drop" locations, including serving as a lookout.

The judge said Tuesday that each could face life in prison if convicted.