While Bungie did not name the individual publicly, multiple sources familiar with the investigation allege that the former employee downloaded the files shortly before leaving the company earlier this year. It is unclear whether the leak was intentional or accidental, but the studio is treating it as a malicious act.

The Marathon reboot, which marks Bungie’s return to the iconic sci-fi franchise, has been under wraps for years. Details about the game’s story, setting, and gameplay mechanics have been scarce, making the leaked art particularly valuable to fans and competitors alike.