U.S. defense contractor Edward Snowden discusses his motivation behind the NSA leak and why he is revealing himself as the whistleblower behind the major story. Courtesy of Laura Poitras and Glenn Greenwald. (Nicki Demarco/Courtesy of Laura Poitras and Glenn Greenwald)

Edward Snowden’s surprising exit from this city was prompted by a mysterious messenger who relayed to the former contractor that he should leave Hong Kong — and that if he tried to go, he would not be stopped, one of his lawyers said Monday.

Unsure whether to trust this person but aware that his options were dwindling, Snowden decided to go for it, said the lawyer, Albert Ho. On Sunday morning, the 30-year-old American, who leaked top-secret U.S. documents, went to the airport with another of his lawyers, used his own passport and boarded an Aeroflot flight to Moscow without special assistance, according to Ho, all while plainclothes police officers hovered around him.

The circumstances of Snowden’s departure from Hong Kong have baffled lawmakers and legal experts here who expected a drawn-out battle in the courts of this semiautonomous region. Instead, experts say, the process was short-circuited — many suspect by Chinese leadership in Beijing who have the last word on Hong Kong’s affairs, especially regarding foreign relations.

Ho, who also is a prominent legislator, portrayed the Hong Kong government as “extremely cautious” and incapable of handling the complications that would come with Snowden’s presence in the city.

The story of how Snowden left the country so easily includes conflicting accounts from Hong Kong and U.S. officials.

Justice Department officials have said Snowden’s passport had been revoked by the time he arrived at the Hong Kong airport Sunday to leave. Hong Kong’s immigration department said in a statement Monday that “so far no notification has been received from the United States Government of Mr. Edward Snowden’s passport being revoked.”

The Justice Department said it received questions from Hong Kong about its request that Snowden be arrested. U.S. officials were in the process of preparing answers to those questions when they learned that Snowden had left the Chinese territory, a Justice Department spokesman said. Officials in Hong Kong said they had no legal basis to hold Snowden because they had not received a response to their queries.

“It doesn’t look good,” said Charles Mok, a Hong Kong legislator and tech expert.

Mok said if Beijing overrode Hong Kong’s legal system in some way, it didn’t bode well for the region’s hopes of remaining truly independent under the “one country, two systems” model.

Mok said it didn’t appear that the U.S. request for a warrant made it to a judge here. Rather, it appeared to have been stopped by the administration of Chief Executive Leung Chun-ying, who is widely viewed as being sympathetic to Beijing.

Ho said he didn’t know if the person who tipped off Snowden was affiliated with the Chinese or Hong Kong government.

On Monday, details also began to emerge about Snowden’s month-long stay in Hong Kong.

After checking out of the Mira Hotel in Kowloon last week, Snowden was shuttled among a few different homes, with at least one in the New Territories area, nearest the border with mainland China. Ho said it was all arranged by “the person who helped him,” whom the lawyer declined to identify. Ho said the person is a Hong Kong resident and “he or she must be well-connected in Hong Kong.”

“He didn’t go out,” Ho said of Snowden. “He spent all his time inside, in a tiny place. But he said it’s okay — with his computer. The saddest day [would be] when he was deprived of his computer.”

Ho said he first met Snowden late Tuesday night, getting into a car at a prearranged spot. Inside the car was Snowden, wearing a hat and sunglasses. Ho recognized him immediately.

Snowden didn’t speak. When they arrived at the home where Snowden was staying, the American whispered that everyone had to put their cellphones in the refrigerator. “Then he became very outspoken,” Ho said.

Snowden was “very smart” and analytical, said his lawyer, although he didn’t seem to have anticipated just how complicated his situation in Hong Kong would become.

“I don’t think he ever had a well-thought out plan,” said Ho, although he added that Snowden seemed to have researched places where he could take refuge.

For two hours that night, Snowden talked with his lawyers, who also included Jonathan Man, an associate at Ho’s firm, and Robert Tibbo, a refu­gee human rights lawyer. To mark Snowden’s birthday later that week — he turned 30 Friday — Ho brought over a large pizza and fried chicken. There was also Snowden’s preferred beverage, Pepsi.

“I really think he’s a kid,” Ho said.

Snowden asked Ho to reach out to the Hong Kong government to get a sense of what it was thinking. Ho made contact with a “high-level” person Friday. The next morning, Snowden told his lawyer about the strange message relayed through an intermediary that he should leave Hong Kong. He asked Ho to talk to the Hong Kong government to see if he could confirm the signal.

Ho again reached out to Hong Kong, and about 6 p.m. Saturday, he received a response he described as, “There’s nothing the government can say.”

Snowden, by then anxious, abandoned a flight to Moscow originally booked for Saturday evening. But Sunday morning, Ho was told that his client was doing it. He was headed to the airport.

Liu Liu and Ricky Li contributed to this report from Beijing.