In a new Thursday court filing , federal prosecutors expanded their accusations against a former National Security Agency contractor. Federal investigators seized at least 50 terabytes of data from Harold Thomas Martin III, at least some of which was "national defense information." 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.

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.

The new filing states that Martin also took “six full bankers’ boxes” worth of paper documents, many which were marked “Secret” or “Top Secret.” The documents date from between 1996 through 2016.

“The weight of the evidence against the Defendant is overwhelming,” court document plainly state.

The documents continue:

For example, the search of the Defendant’s car revealed a printed email chain marked as “Top Secret” and containing highly sensitive information. The document appears to have been printed by the Defendant from an official government account. On the back of the document are handwritten notes describing the NSA’s classified computer infrastructure and detailed descriptions of classified technical operations. The handwritten notes also include descriptions of the most basic concepts associated with classified operations, as if the notes were intended for an audience outside of the Intelligence Community unfamiliar with the details of its operations.

The government also presents new biographical information about Martin, noting that he has “obtained advanced educational degrees and has taken extensive government training courses on computer security, including in the areas of encryption and secure communications.”

Martin allegedly used a “sophisticated software tool which runs without being installed on a computer and provides anonymous Internet access, leaving no digital footprint on the Machine,” and he tried “to run operating systems on his machines that would not leave any forensic evidence of his computer activities.” That could suggest Martin was using TAILS or another USB-bootable operating system in conjunction with Tor or a VPN.

While the new filing does not specifically mention it, the New York Times reported Wednesday that Martin may have been involved in the “Shadow Brokers” dump of NSA exploits.

As the Times reported:

But so far, the investigators have been frustrated in their attempt to prove that Mr. Martin deliberately leaked or sold the hacking tools to the Shadow Brokers or, alternatively, that someone hacked into his computer or otherwise took them without his knowledge. While they have found some forensic clues that he might be the source, the evidence is not conclusive, according to a dozen officials who have been involved in or have been briefed on the investigation.

The former NSA contractor is accused of owning 10 guns , only two of which were registered, including an “AR-style tactical rifle.” Martin’s wife, Deborah Shaw, was “very upset to learn about the Defendant’s arsenal.” According to the new court filing, Shaw asked all the firearms to be removed from her home, and they were taken away by the FBI.

Among the documents seized, investigators found a letter sent in 2007 to Martin’s colleagues, in which he criticizes the government’s information security practices and refers to those same co-workers as “clowns.”

Martin is set to appear before US Magistrate Judge Beth P. Gesner for a detention hearing on Friday at 2:15pm ET in Baltimore.