How the U.S. and Julian Assange reached a plea deal - and what it means

After more than thirteen years in England, including five years spent in prison, Julian Assange pleaded guilty in the Northern Mariana Islands, a far-flung US territory in the Pacific, and walked out of court a free man.

The timing -- and location -- of the plea deal seemed to have come out of nowhere.

But an agreement between Assange, an Australian citizen who leaked US national security secrets in 2010, and American prosecutors had been moving forward in earnest for months.

- When did discussions around a deal start?