The suspect, Harold Martin, was a contractor for the National Security Agency. His arrest followed news of a devastating disclosure of government hacking tools by a mysterious internet group calling itself the Shadow Brokers . It seemed to some that the United States might have found another Edward Snowden, who also had been a contractor for the agency.

"You're a bad man. There's no way around that," one law enforcement official conducting the raid told Martin, court papers say. "You're a bad man."

Later this month, about three years after that raid, the case against Martin is scheduled to be resolved in Baltimore's federal court. But the identity of the Shadow Brokers, and whoever was responsible for a leak with extraordinary national security implications, will remain a public mystery even as the case concludes.