Mr. Young said that based on his research, it usually took three to four days in previous cases for a request from overseas to lead to an arrest.

“It’s really about good faith and wanting to be a strong partner in these things, or keeping a distance,” he said, adding that Hong Kong had clearly chosen to keep its distance from the United States.

Security experts and democracy proponents say that mainland China’s domestic surveillance operations in Hong Kong are far more extensive than the American effort. But those operations have largely disappeared from public discussion as attention has focused on the many details released by Mr. Snowden.

Martin Lee, the founding chairman of the Democratic Party but now mostly retired from day-to-day politics, has been a lonely voice here in questioning the Hong Kong government’s handling of Mr. Snowden. Mr. Lee said that he was concerned whether Hong Kong had fully followed its obligations to detain or surrender fugitives under its bilateral agreement with the United States.

“It looks like the government turned a blind eye to all these formalities and let him go,” he said.

Mr. Lee said that if Mr. Snowden had stayed, his presence would have focused more international attention on the territory’s annual pro-democracy protest on July 1. “Now the guy’s gone, nobody is interested in Hong Kong,” he said.

The Hong Kong government considered in advance the possibility that the United States might retaliate for the decision to let Mr. Snowden leave, a person with detailed knowledge of the Hong Kong government’s deliberations said. Hong Kong has long asked that the United States issue visas on arrival to its citizens, instead of requiring them to apply in advance at the U.S. Consulate here. That pursuit of easier visa access could be hurt by the decision to allow Mr. Snowden’s departure, said the person, who requested anonymity because of diplomatic sensitivities.

But the Hong Kong government concluded that the United States was not likely to grant visas on arrival anytime soon anyway, the person said. The United States requires residents of mainland China to obtain visas in advance, and Hong Kong has been under Chinese rule since Britain returned it in 1997.