Where did Edward Snowden – The NSA Leaks come from?

Edward Snowden, the famous NSA leaker living in Russia, revealed a global, mammoth spying program from our federal government. From spying on its citizens (phone records, emails, etc.) to spying on world leaders, only now are we beginning to see the true scope of this program. Where did it come from? How extensive was the spying? Was this a “state crime?” (i.e. government crime) If so, who should be punished and how?