US government investigators began an urgent search for Edward Snowden several days before the first media reports were published on the government's secret surveillance programs, people familiar with the matter said on Wednesday.
Snowden, who has admitted to providing details of the top-secret programs, had worked on assignment at a Hawaii facility run by the National Security Agency for about four weeks before he said he was ill and requested leave without pay, according to the sources who spoke on condition of anonymity.
When Snowden failed to return, that prompted a hunt for the contractor, first by his employer Booz Allen Hamilton and then by the US government, they said.
Snowden, 29, was known among colleagues as a very gifted "geek," according to one of the sources, who added, "This guy's really good with his fingers on the keyboard. He's really good."
His job as a systems administrator would have afforded Snowden very wide access to servers containing classified information at the NSA, and possibly other US intelligence agencies, the same source said, without giving specifics.
US officials do not yet know the extent to which Snowden was able to access intelligence databases, nor have they identified all the secret material he might have downloaded before leaving for Hong Kong, according to three sources.
Several sources said that as a systems administrator, Snowden would have been unable to actively spy on people, even though he told the Guardian newspaper, "I, sitting at my desk, certainly had the authority to wiretap anyone, from you or your accountant, to a federal judge, to even the President."
Snowden already had a Top Secret clearance before he joined Booz Allen in April, two sources said, adding that he likely obtained that clearance - which involves passing a polygraph exam - when he previously worked for the Central Intelligence Agency.
For his first week or two with Booz Allen, Snowden attended training sessions near Fort Meade, the Maryland military installation where NSA headquarters is located and where numerous agency contractors have offices.
After that, Snowden moved to take up his assignment with a company team based at the NSA installation in Hawaii. He was only on the job for around four weeks when he told his employers he was ill and requested leave without pay, the sources said.
When Booz Allen checked in with him, Snowden said he was suffering from epilepsy and needed more time off. When he failed to return after a longer period, and the company could not find him, it notified intelligence officials because of Snowden's high-level security clearance, one of the sources said.
Government agents spent several days in the field trying to find Snowden, according to the source, but they were unable to do so before the first news story based on Snowden's revelations appeared in the Guardian and then in the Washington Post.
The government did not know Snowden was the source for the stories until he admitted it on Sunday, the sources said. A spokesman for Booz Allen Hamilton said the company had no comment beyond its earlier statements. Booz had previously said it fired Snowden for violating its "code of ethics and firm policy."