Teixeira, 21, is accused of orchestrating the most damaging leak of U.S. classified documents in a decade, posting a trove of highly sensitive information in an online chat forum.
From there, they spread across the internet.
The documents involved assessments of Ukraine's military capacity against invading Russian forces - and showed Washington had apparently spied on allies Israel and South Korea, among other sensitive details.
Prosecutors pushing for him to remain detained pending trial filed multiple documents in support of their argument on Wednesday, including copies of three partially redacted U.S. Air Force memoranda showing that Teixeira had been caught behaving suspiciously on multiple occasions.
One dated September 15, 2022 says that Teixeira was "observed taking notes on classified information" and was "instructed to no longer take notes in any form on classified intelligence."
Another from the following month shows that the problem persisted, with Teixeira "potentially ignoring the cease-and-desist order on deep diving into intelligence information" that he was given in September.
He was told to "continue to cease-and-desist on any deep dives into classified intelligence information and focus on his job," the document says.
That, too, was ignored, however, as Teixeira was seen in late January 2023 "viewing content that was not related to his primary duty and was related to the intelligence field," a third document says.
Teixeira was arrested in April following a week-long probe and charged with two counts that carry maximum prison sentences of 10 years and five years.
Despite the multiple warnings on mishandling classified information, Teixeira still held a "Top Secret" security clearance at the time of his arrest, according to an FBI affidavit.
A judge is expected to rule Friday on prosecutors' motion for Teixeira's continued detention.
