ISLAMABAD, PAKISTAN - Raymond Davis, the American CIA contractor jailed in the fatal shooting of two Pakistani men last month, has quickly assumed the role of Pakistan's public enemy No. 1. But not far behind him are those who have come to be known as "Raymond Davises."

Davis's name has become a byword for a presumed army of hundreds, perhaps thousands, of shadowy American operatives stalking Pakistani streets. So important is his silence to protecting their mission, according to some Pakistani media reports, that the United States might spring him from prison in an action-movie-style rescue operation - or have its agents poison him.

"The Americans want to destroy Pakistan," said Aslam Hayat, 54, a construction worker who was speaking after prayers at a mosque in Rawalpindi. "That's why people like Davis are roaming all around the country, assigned with different tasks against our country."

Such conspiracy theories have long dominated discussions here about the U.S.-Pakistan relationship, in part because they are occasionally confirmed - as one was this week when U.S. officials said that Davis is a security contractor for the CIA. They had previously described him as a diplomat entitled to immunity from prosecution, a characterization they still maintain is accurate.

But officials and analysts said the speculation about multitudes of American gunslingers also reflects widespread hostility toward the U.S. presence, which has increased since the shooting and could represent a particularly ominous turn for the United States' rapidly expanding mission in Pakistan.

As the Obama administration has boosted economic and development assistance for Pakistan over the past two years, it has deployed U.S. diplomats and aid workers more widely to implement education programs, flood relief and other projects. The apparently growing belief that many Americans work as sinister agents could imperil those efforts or endanger those carrying them out, U.S. and Pakistani officials said.

"It's going to be very difficult, moving forward, for a lot of regular diplomats and development workers to work here without constantly having to deal with a sense of insecurity on the part of the Pakistanis - accusations, suspicion, skepticism," said Mosharraf Zaidi, a commentator and policy adviser who has worked as a contractor for the U.S. Agency for International Development.

In the capital, Islamabad, the United States is spending $1 billion to expand its fortified embassy compound to support hundreds of new employees, construction that is now fueling fresh scrutiny in the Pakistani media. Dozens of additional diplomats and aid workers are being assigned to consulates in Karachi, Peshawar and Lahore, the eastern city where Davis shot the Pakistanis.

U.S. officials said Davis, 36, was working with a team of CIA contractors and an agency employee out of a safe house in Lahore. He has said that he shot the two Pakistanis in self-defense as they tried to rob him.

It is unclear how many of the U.S. mission's personnel are private security contractors or intelligence agents, many of whom work alongside Pakistani agents on counterterrorism operations, including the CIA drone program. A U.S. Embassy spokeswoman declined to provide figures; according to data provided by the Pakistani Embassy in Washington, 3,555 U.S. diplomats, military officials and employees of "allied agencies" were issued visas in 2010, most of which were valid for three months.

Pakistani commentators and opposition parties have filled that vacuum of information in recent days with numbers of their own. In a recent newspaper column, Raoof Hasan, a media adviser to the chief minister of Punjab province, of which Lahore is the capital, wrote of "scores of other Raymonds roaming the roads." Last week, the chief of Jamaat-e-Islami, a religious party, told a gathering of tribal elders that there are "thousands of Raymond Davises."

U.S. officials, for their part, have said little about Davis's duties. Although Pakistan is considered a high-risk environment, Pakistani officials said diplomats here do not typically carry loaded Glock pistols, as Davis did. According to a senior U.S. official, Davis, a former Special Forces soldier, was not authorized to carry a weapon in Pakistan. Another senior U.S. official disputed that, saying, "After all, he was performing security duties there. What are security officers supposed to do?"

But as outrage over the Davis shooting mounts, suggestions that all U.S. personnel are spies are feeding popular suspicion about the battery of American programs here and renewing reservations about the U.S. presence in general.

"They may be justifying their work as for an NGO or other U.S. agency, but the prime purpose of their stay in the city is to spy," Fakhr-e-Alam Khan, a leader of a religious party, said of U.S. workers in the northwestern city of Peshawar.

The rhetoric has alarmed U.S. officials, who have struggled to win hearts and minds in a nation where the opacity of some of their activities has made them unpopular, but where that unpopularity has in turn made them operate even more privately.

In recent weeks, Pakistani media have reviewed incidents of past traffic violations and accidents involving U.S. officials in armored vehicles, though police said in interviews that they have recorded no such cases recently outside of the Davis incident, in which a U.S. consular vehicle hit and killed a bystander. Several reports have described imperious behavior by U.S. officials visiting Davis, an accusation the embassy has publicly rejected.

Even some typically pro-U.S. analysts have faulted the United States and President Obama for publicly pressuring Pakistan to release Davis, saying such moves affirm perceptions of American arrogance while doing little to help Pakistan's weak civilian government navigate a thorny domestic problem.

"It has certainly added to all the wrong kinds of impressions . . . about the United States in Pakistan," said Tariq Fatemi, a former Pakistani diplomat who has often written favorably about the United States.

Hafiz Muhammad Usman, a businessman in Lahore, said that since Davis's arrest he has observed a decline there in people he is sure were American "agents" - people who he said used to swarm the streets in black jeeps.

Even so, he said, the whole episode has convinced him that no amount of U.S. assistance is worth allowing Americans into Pakistan or its airspace, adding that he has switched from supporting Pakistan's main opposition party to backing a faction led by Imran Khan, a former cricket star and staunch U.S. detractor.

"Aid is only for the influential," said Usman, 29. "We need a ruler like him who can have the courage to look into the eyes of Americans and kick them out of our country."

Special correspondents Aoun Sahi in Lahore, Haq Nawaz Khan in Peshawar and Shaiq Hussain in Islamabad contributed to this report.