Earlier quoted context omitted.
First of all, there have been several NSA whistleblowers that have spoken on this issue. William Binney even gave the CCC a copy of some code that was a similar model to what his team initially designed for the NSA. Second, his current job at a contractor is relatively new, but before joining Booz Allen he worked directly under an intelligence agency.
Where is it recorded that he worked directly under an intelligence agency? (Honest question; i've not found that.)
In 2007 he was stationed in Switzerland (CIA), he left the CIA in 2009.
In 2009 he started to work for a private contractor in the U.S and Japan which had him stationed at a NSA facility.
I don't get all the media reports that he only been on the inside for 3 months. This adds up to 7+ years.
It all on his wiki page with footnotes to sources.