The National Security Operations Center at NSA, photographed in 2012—the nerve center of the NSA’s “signals intelligence” monitoring. (credit: National Security Agency)

In a new Thursday court filing, federal prosecutors expanded their accusations against a former National Security Agency contractor. Feds now accuse Harold Thomas Martin III of stealing at least 50 terabytes of classified material. The incident is believed to be the largest heist of secret data from the NSA, far larger than what former contractor Edward Snowden took.

Prosecutors also said that Martin should remain locked up and noted that he will soon be charged with violations of the Espionage Act. That law, which dates back nearly a century, is the same law that was used to charge Chelsea Manning and Snowden among others. If convicted, violators can face the death penalty.

United States Attorney Rod Rosenstein and two other prosecutors laid out new details in the case against Martin, whose arrest only became public earlier this month. Martin had been a contractor with Booz Allen Hamilton and possessed a top secret clearance.