Edward Snowden, who acknowledged leaking top-secret documents about extensive U.S. surveillance of telephone calls and Internet communications, claimed in an unusual live Web chat Monday that he sees no possibility of a fair trial in the United States and suggested that he would try to elude authorities as long as possible.

The U.S. government has “openly declar[ed] me guilty of treason and [said] that the disclosure of secret, criminal and even unconstitutional acts is an unforgivable crime,” he said. “That’s not justice, and it would be foolish to volunteer yourself to it if you can do more good outside of prison than in it.”

Snowden’s remarks came in a question-and-answer session on the Web site of Britain’s Guardian newspaper. The Guardian and The Washington Post recently published articles about National Security Agency surveillance programs based on documents provided by Snowden. He is believed to have taken the classified material while working as an NSA contractor in Hono­lulu for the consulting firm Booz Allen Hamilton.

The spectacle of Snowden using the Internet to defend himself and level new accusations was the latest chapter in the unfolding story. The Guardian did not say where Snowden was when he responded to written questions from its reporters and the public. In a note on the site, the newspaper said the discussion was subject to “Snowden’s security concerns and also his access to a secure Internet connection.”

Snowden, 29, emerged June 9 from his status as an anonymous source for the articles. At the time, he was staying in an upscale hotel in Hong Kong, which he said he had chosen because he felt he might win asylum. He gave an interview to a Hong Kong newspaper last week, but since then he has disappeared.

Snowden said in the chat that the U.S. government has accused him of treason, but he faces no known charges. Justice Department officials said a criminal investigation is underway to determine the extent of the damage created by Snowden’s leaks and the nature of any charges he might face.

One critical aspect of the damage assessment is how Snowden, as a low-level contractor, could have gained access to highly sensitive documents, including a top-secret order from a secret court compelling a unit of Verizon to turn over phone-call records, according to U.S. officials.

A former Justice Department official, who spoke on the condition of anonymity because he was not authorized to discuss the case publicly, said officials are probably gathering forensic material that would back up possible criminal charges. They could then file criminal charges in federal court in the District of Columbia or Hawaii or indict Snowden under seal. The official said prosecutors might choose to seal the indictment so Snowden would not know that he was subject to detention and arrest.

“Because this case is so extraordinarily high-profile, they have to be proceeding gingerly and getting all their ducks in a row to figure out what happened before rushing to indict Snowden,” the former official said. “Given the timing of this coming after the [Associated Press] and Fox News case and other leak cases that have not gone well for the department, I think they want to be exceedingly careful. But I wouldn’t be surprised if something happens soon.”

The official also said the Justice Department’s Office of International Affairs would already be negotiating with the Hong Kong authorities over a possible arrest and extradition.

In answering questions for 90 minutes, Snowden defended himself and sought to justify his actions. “All I can say right now is the U.S. government is not going to be able to cover this up by jailing or murdering me,” he said. “Truth is coming, and it cannot be stopped.”

The leaks, which covered two extensive NSA electronic surveillance programs, sparked an international debate and led to praise and condemnation for the former Maryland resident.

Snowden said leaving the United States “was an incredible risk” because NSA employees must declare any foreign travel 30 days in advance. He told his employers that he was taking time off for medical treatment.

“There was a distinct possibility I would be interdicted en route, so I had to travel with no advance booking to a country with the cultural and legal framework to allow me to work without being immediately detained,” he said.

While in Hong Kong, he showed documents to the South China Morning Post newspaper that said the U.S. government had hacked into hundreds of targets in Hong Kong and mainland China.

He defended his leak Monday, saying he did not reveal any operations against legitimate military targets. “I pointed out where the NSA has hacked civilian infrastructure such as universities, hospitals and private businesses because it is dangerous,” he said. “These nakedly, aggressive criminal acts are wrong no matter the target.”

He also responded to speculation by former vice president Richard B. Cheney and others that he provided classified information to the Chinese government in exchange for asylum. “I have had no contact with the Chinese government,” he said. “Ask yourself: If I were a Chinese spy, why wouldn’t I have flown directly into Beijing?”

Snowden also criticized the Obama administration for what he called “overly harsh responses to public-interest whistleblowing,” citing prosecutions of several government employees accused of leaking classified information. Among the cases he mentioned was that of Army Pfc. Bradley Manning, who faces possible life in prison in a court-martial, underway at Fort Meade in Maryland, over his leaking of documents to the anti-secrecy group WikiLeaks.

“These draconian responses simply build better whistleblowers,” he said. “If the Obama administration responds with an even harsher hand against me, they can be assured that they’ll soon find themselves facing an equally hard public response.”