In the final filing before a second custody hearing in a week, prosecutors said Thursday afternoon that a former National Security Agency contractor accused of removing massive amounts of secret data and documents should remain in custody.

Among that trove of data, investigators say they found “numerous names of intelligence officers of the United States” who are serving abroad.

When Martin was arrested in August, investigators seized 50TB worth of data and many other printed and classified documents from Martin’s home in suburban Maryland. If all of this data was indeed classified, it would be the largest such heist from the NSA, far larger than what former contractor Edward Snowden took.

“Although still undergoing review, it is estimated that a substantial portion of the 50 terabytes of digital information seized from the Defendant contains highly classified information,” Harvey Eisenberg, and other prosecutors wrote in an explanation of what Top Secret/Sensitive Compartmented Information (TS/SCI) intelligence is, underscoring that it is considered to be “irreplaceable once compromised.”

As Eisenberg continued:

As an example, information stolen by the Defendant includes numerous names of intelligence officers of the United States. These officers operate under cover outside the United States, and putting the secrecy of their identities at risk by removing information about those identities from appropriate, secure storage not only endangers the lives and safety of those officers and the individuals with whom they work, but also risks exposure of American intelligence operations. Additionally, numerous intelligence sources and methods for highly sensitive intelligence operations would be rendered nearly useless should they fall into the wrong hands.

Last week, US Magistrate Judge A. David Copperthite ruled that Harold Martin was a flight risk and should remain behind bars pending trial. Earlier this week, Martin’s defense attorneys asked a more senior judge, US District Judge Richard D. Bennett, to overrule that decision.

Judge Bennett will hold a hearing on the matter later on Friday, October 28, at 2:30pm ET in federal court in Baltimore.