The contractor is suspected of taking the source code used by the agency to hack the computer systems of foreign governments.
According to an official, Harold Thomas Martin, 51, of Maryland, worked for Booz Allen Hamilton, the same company that employed whistleblower Edward Snowden, who made damaging disclosures about the US government’s surveillance and spying activities in 2013.
The company said in a statement when it “learned of the arrest of one of its employees by the FBI,” he had been immediately fired and the firm had offered full cooperation to the agency.
Martin’s arrest in August came just weeks after a leak of classified source code used by the NSA to hack computer systems, such as those of Russia, China, Iran and North Korea.
The contractor, who had top secret national security clearance, has been accused of the theft of classified government material.
Martin faces up to 10 years in prison if convicted.