US officials have revealed that NSA whistleblower Edward Snowden was able to smuggle the classified documents out of a Hawaii facility using a thumb drive, which are banned inside of agency locations, reports the Los Angeles Times. Reportedly, investigators were able to discern what documents Snowden took and which server he took them from. However, it has not been made public whether or not Snowden is in possession of additional documents. The FBI is now conducting a criminal investigation of his actions and intends to prosecute him.

The thumb drive ban was implemented by the Pentagon in 2008, following a malware scare on agency computers, reports the LA Times. But despite the ban, portable storage devices have still found their way into secured locations — Bradley Manning used CDs and thumb drives to transfer classified information back in 2010. Reportedly, some NSA employees may actually be allowed to carry thumb drives based on their job details. "There are people who need to use a thumb drive and they have special permission," an unnamed, ex-NSA official told the LA Times. "But when you use one, people always look at you funny."