A federal judge has overruled a magistrate and ordered a Defense Department civilian and U.S.-Turkish dual citizen to remain jailed while he awaits trial on accusations he mishandled classified documents.

Gokhan Gun, 50, of Falls Church, was arrested outside his home on Aug. 9. Prosecutors say he was on his way to the airport for a trip to Puerto Vallarta, Mexico, and was carrying papers, including a document that was marked Top Secret. A search of his home found other classified documents.

Gun said he was going on a fishing trip.

Shortly after his arrest, U.S. Magistrate Judge Ivan Davis said Gun could await trial on home detention, despite objections from prosecutors, who considered Gun both a flight risk and a danger to disseminate government secrets. Prosecutors immediately appealed, keeping him in custody.

At a hearing Thursday in Alexandria, U.S. District Judge Michael Nachmanoff sided with prosecutors and ordered that Gun remain jailed pending trial.

Gun worked since September as an electrical engineer with the Joint Warfare Analysis Center and held a Top Secret security clearance. He was born in Turkey and became a U.S. citizen in 2021.

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Prosecutors cited a review from an Air Force intelligence expert who concluded that the Top Secret document found in Gun’s backpack at the time of his arrest referenced “research and development of a highly technical nature” that could enable adversaries to harm national security.

Prosecutors have also said they may file more serious charges against Gun under the Espionage Act.

Gun’s lawyer, Rammy Barbari, said in court papers that it is only speculation that Gun intended to take the backpack with the Top Secret document with him on his Mexico trip. He also said that Gun printed out thousands of unclassified documents and suggested that the classified documents could have been printed by mistake.

Prosecutors, though, said Gun began printing out large amounts of unclassified documents just a few months after obtaining his security clearance, often late in the day after co-workers had gone home. They say he then began mixing in classified documents, and printed out his largest batch of classified documents just two days before his arrest.

That change in his printing habits prompted agents to obtain the search warrants, they said.