WASHINGTON (AP) — The massive classified documents leak by an Air Force service member earlier this year was made worse by the intentional failure of multiple officials to take required action on his suspicious behavior, the Air Force inspector general reported Monday.

Massachusetts Air National Guard member Jack Teixeira is accused of leaking highly classified military documents on a social media platform.

In its investigation of the leaks, the Air Force inspector general found both security gaps where personnel had access to classified documents without supervision and instances in which Airman 1st Class Teixeira was caught violating security policies but none of the personnel who caught him took the actions necessary in response.

“Based on the preponderance of the evidence gathered during the investigation, three individuals in the unit who understood their duty to report specific information regarding A1C Teixeira’s intelligence-seeking and insider threat indicators to security officials, intentionally failed to do so,” the inspector general found.

In response, the Air Force said it took action against 15 people, ranging from relieving personnel from their positions, including command positions, to non-judicial punishment under Article 15 of the Uniform Code of Military Justice.

Teixeira, who’s 21, has been behind bars since his April arrest on charges stemming from the most consequential intelligence leak in years. He is charged under the Espionage Act with unauthorized retention and transmission of classified national defense information. He has pleaded not guilty, and no trial date has been set. Prosecutors said in a court filing last week that the two sides have not yet engaged in “substantive” plea discussions.

The documents released on social media revealed sensitive U.S. intelligence on the Russia-Ukraine war, the Middle East and an array of other topics.

Teixeira enlisted in the Air National Guard in 2019 and began around January sharing military secrets with other Discord users, authorities said — first by typing out classified documents and then sharing photographs of files that bore SECRET and TOP SECRET markings.

Teixeira worked as a cyber transport systems specialist, essentially an information technology specialist responsible for military communications networks. As such, Teixeira was part of a three-person crew that had unsupervised access at night to an open storage Top Secret-Secret Compartmentalized facility to perform maintenance inspections.

“At times, members were required to perform preventive maintenance inspections and other tasks, which required individuals to be on their own for hours, unsupervised in other parts of the facility,” the IG found. “Further, no permission controls were in place to monitor print jobs, and there were no business rules for print products. Any night shift member had ample opportunity to access (classified) sites and print a high volume of products without supervision or detection.”