Richard Esposito, Matthew Cole and Robert Windrem
NBC News 
August 29, 2013
Edward Snowden accessed some secret national security documents by assuming the electronic identities of top NSA officials, said intelligence sources.
“Every day, they are learning how brilliant [Snowden] was,” said a former U.S. official with knowledge of the case. “This is why you don’t hire brilliant people for jobs like this. You hire smart people. Brilliant people get you in trouble.”
Snowden was a Honolulu-based employee of Booz Allen Hamilton, an NSA contractor. His job gave him system administrator privileges on the NSA’s intranet, NSAnet. He reportedly used his privileges to download 20,000 documents.
The NSA still doesn’t know exactly what Snowden took. But its forensic investigation has included trying to figure out which higher level officials Snowden impersonated online to access the most sensitive documents.