Life and times of an intelligence leaker

2006: Snowden is hired by the Central Intelligence Agency as a technical expert. He is given top-secret clearance.

2007-09: Snowden is posted to Geneva, Switzerland, under diplomatic cover as an IT and cybersecurity expert for the CIA, a position that gives him access to a wide array of classified documents.

Late 2009-March 2012: Snowden's supervisor at the CIA places a critical assessment of Snowden's behavior and work habits in his personal file, and voices suspicion that he tried to "break into classified computer files to which he was not authorized to access". Snowden leaves the CIA and starts work as an NSA contractor assigned by Dell — one of 854,000 contractors with top-secret clearance working for the federal government. Over the next few years, he switches between assignments with the NSA and the CIA for Dell, including a stint at an NSA facility in Japan that lasts until March 2012.

March 2012: Snowden moves to Hawaii to work at an NSA facility as a Dell employee.

Dec 1, 2012: Snowden contacts Glenn Greenwald, a lawyer and columnist for British newspaper The Guardian.

January 2013: Snowden contacts Laura Poitras, a documentary filmmaker.

March 2013: He seeks a new contractor job at consulting company Booz Allen Hamilton at the same NSA facility in Hawaii.

May 2013: Snowden begins sending documents to Poitras, Greenwald and Barton Gellman of The Washington Post.

June 5, 2013: First revelations arising from the documents provided by Snowden are published in The Guardian's article about the NSA's collection of domestic email and telephone metadata from communication technology company Verizon as part of what is later revealed to be an even broader collection effort.

June 6, 2013: The Guardian and The Washington Post publish an article about the NSA program Prism, which forces the biggest US internet companies to hand over data on domestic users.

June 8, 2013: The Guardian publishes NSA slides on the data-mining tool Boundless Informant, which show the NSA collected nearly 3 billion pieces of intelligence in the US in February 2013 alone.

June 9, 2013: The Guardian reveals Snowden as the source of the NSA leaks.

June 11, 2013: The European Union demands US assurances that Europeans' rights are not infringed upon by the newly revealed surveillance programs. Snowden is fired by Booz Allen Hamilton.

June 14, 2013: The US Justice Department charges Snowden with theft, unauthorized communication of national defense information, and willful communication of classified communications intelligence information to an unauthorized person.

June 23, 2013: Snowden leaves Hong Kong for Ecuador, with a planned stopover in Russia. He is stranded at Sheremetyevo International Airport in Moscow after US authorities rescind his passport. He spends the next month living in limbo in the airport's transit center.

Aug 1, 2013: He is granted temporary asylum by Russian authorities as they consider his application for permanent political asylum.

Oct 2, 2013: At a US Senate hearing on the Foreign Intelligence Surveillance Act, Director of National Intelligence James Clapper tells lawmakers that Snowden's leaks have aided the US' enemies and done great damage to its allies.

Oct 14, 2013: The Washington Post reports that the NSA collects more than 250 million email inbox views and contact lists each year from online services such as Yahoo, Gmail and Facebook. The documents are provided by Snowden.

Dec 16, 2013: US District Judge Richard Leon rules that the NSA's gathering of data on all telephone calls made in the US appears to violate the Constitution's protection against unreasonable searches. But Leon, an appointee of former president George W. Bush, puts his ruling on hold to allow the government to appeal.

Dec 17, 2013: Snowden posts an open letter to Brazil, offering to help investigate US surveillance of Brazilian citizens.

Feb 7, 2014: Based on Snowden documents, NBC News reports that British spies have developed "dirty tricks "for use against nations, hackers, terror groups, suspected criminals and arms dealers that include releasing computer viruses, spying on journalists and diplomats, jamming phones and computers, and using sex to lure targets into "honey traps".