Whether Snowden has remained in Hong Kong or fled to another country - like Iceland, where he has said he might seek asylum - the charges would strengthen the Justice Department's hand if it tries to extradite him to the United States. One government typically must charge a suspect before another government will turn him over.
"There's no hesitation" about charging Snowden, one of the U.S. officials said, explaining that law enforcement officials had not been deterred by the debate inside and outside the administration about its leak investigations.
The brazenness of the disclosures about some of the National Security Agency's surveillance programs and Snowden's admission in the newspaper The Guardian on Sunday left little doubt among law enforcement officials, the official said.
Officials at the White House, the Justice Department and intelligence agencies declined to comment Monday on the investigation and on Snowden.
Sen. Dianne Feinstein, D-Calif., who is the chairwoman of the Intelligence Committee and has praised the programs' effectiveness, said the panel would hold a closed briefing for all senators Thursday to hear from NSA, FBI and Justice Department officials. A similar closed hearing is scheduled for Tuesday in the House.
In Hong Kong, legal experts said the government was likely to turn over Snowden if it found him and the United States asked, although he could delay extradition, potentially for months, with court challenges. The Hong Kong authorities have worked closely with U.S. law enforcement agencies for years and have usually accepted extradition requests under long-standing agreements, according to Regina Ip, a former secretary of security who serves in the territory's legislature.
"He won't find Hong Kong a safe harbour," Ip said.
The Mira Hotel said Snowden had stayed at the hotel but had checked out Monday.
The Justice Department investigation of Snowden will be overseen by the FBI's Washington field office, which has considerable experience prosecuting such cases, according to one of the officials.
The department's investigation into Snowden is one of at least two continuing government inquiries. The NSA began trying to identify and locate the leaker when The Guardian published its first revelations Wednesday, and there were indications that agency officials considered Snowden a suspect from the start.
According to Kerri Jo Heim, a real estate agent who handled a recent sale of a Hawaii home that Snowden had been renting, the police came by the house Wednesday morning, perhaps even before The Guardian published its story. The police asked Heim if they knew Snowden's whereabouts.
Snowden moved last spring to the house on Oahu, 15 miles northwest of Honolulu, in a neighbourhood populated by military families tied to the nearby Schofield Barracks, an Army base.
The NSA investigation is also examining the damage that the revelations might have on the effectiveness of the agency's programs.
James R. Clapper Jr., the director of national intelligence, said over the weekend on NBC News that he was concerned about "the huge, grave damage it does to our intelligence capabilities."
He did not cite specific examples of the damage caused by the disclosures.
Members of Congress criticized Snowden on Monday. He "has damaged national security, our ability to track down terrorists, or those with nefarious intent, and his disclosure has not made America safer," said Rep. Jim Langevin, D-R.I., a member of the House Intelligence Committee.
The string of articles describing the surveillance programs will probably prompt a broad review within government agencies on granting federal workers and private contractors access to classified data.
Three years ago, the State Department significantly tightened access to its classified data, in reaction to the release of department cables to WikiLeaks by a low-level intelligence analyst, Pfc. Bradley Manning.
In Snowden's case, similar questions are emerging: Why would a relatively low-level employee of a large government contractor, Booz Allen Hamilton, posted in Hawaii for only three months, have access to classified presidential directives or a PowerPoint presentation on Internet surveillance, and how could he download them without detection?
At a White House briefing Monday, Jay Carney, the press secretary, went out of his way not to discuss Snowden, referring to him as "the individual." Carney declined to say whether President Barack Obama had watched a video in which Snowden explained his motivations and argued that the U.S. government conducted too much surveillance of its citizens.
U.S. officials cited the continuing inquiry as the reason for the low-key approach. By keeping silent on Snowden and his case, the Obama administration also avoids elevating his status, even as whistle-blower advocacy groups championed him and his disclosures Monday. A petition to pardon Snowden, posted on the White House website, attracted more than 25,000 electronic signatures by Monday afternoon.
In a separate case, a federal appeals court ruled Monday against a civil-liberties advocacy group that challenged the constitutionality of the NSA's warrantless wiretapping program. The 9th U.S. Circuit Court of Appeals, based in San Francisco, refused to overturn a lower-court ruling dismissing the lawsuit, brought by the Centre for Constitutional Rights.
The suit initially sought to end the Bush-era wiretapping program and later challenged the constitutionality of new legislation passed by Congress after the original program was disclosed by The New York Times in December 2005.