Harold "Hal" Martin, 54, had worked for 23 years as a contractor for various contracting agencies and maintained a government clearance throughout his career.
Prosecutors described him as a hoarder who took home a whopping 50 terabytes of files, including a number of classifieds he stored on drives in his home and car.
Martin's Arraignment is scheduled for a Thursday afternoon in Baltimore, where he wants to go to a guilty plea, Wyda told CNN.
NSA files, including reports on future plans, spy tools, and technical descriptions of NSA communications programs.
While Martin is accused of being the most prolific Of them, the NSA has experienced a number of "insider threats" in recent years, in which agency employees and contractors have violated classification laws to remove agency files.
A Booz Allen Hamilton spokesman, James Fisher, told CNN the company "closely cooperating with the federal government throughout" the Martin case.