But their ability to find work at the cargo screening facility of one of the nation's busiest seaports troubled Charles DeMore, a federal agent charged with protecting sensitive and secure U.S. facilities.

"When someone uses fraud or false documents to gain access to a major cargo hub like the Port of Oakland, we have no way of knowing who they really are or what their motives might be," DeMore said following the workers' October arrests.

And yet the story of what happened in Oakland - where contractors had been granted the authority to bypass normal security measures and then allowed undocumented foreign workers into the shipyard - has repeated itself at military bases, nuclear plants, chemical plants, airports and seaports across the United States.

The most recent case? The Dugway Proving Grounds, a U.S. Army biological and chemical testing facility 80 miles southwest of Salt Lake City, where nine illegal workers were arrested inside the base gates after being brought in by a subcontractor.

Although immigration officials have found a pattern of violations that one agent said was a virtual "playbook" for secretly moving people into the nation's most sensitive places, authorities have reacted slowly - and in some cases, not at all.

In most cases, Immigration and Customs Enforcement spokeswoman Virginia Kice said, the undocumented workers arrested at the facilities are not thought to have terrorist intentions.

But, she said, "we're talking about sites that could cripple the country if undermined."

A trusting system: In most cases, getting a job at Dugway Proving Ground means interviews, background checks and waiting lists.

But there are a few exceptions: Like at most military facilities, construction, maintenance and janitorial work is contracted out.

And so for a few individuals, getting a job recently at Dugway meant simply hopping into the truck of a subcontractor who was looking for some drywallers willing to work cheap.

Dugway officials say they've always asked contractors to inform them if any of their workers are from foreign countries. But until last month, they trusted that contractors were being forthright.

While some might see that as an overly trusting system for such a highly sensitive facility, it's not unusual. A review of dozens of similar cases shows that contractors and subcontractors are routinely given authority to clear their own workers through security.

Among the hundreds arrested and deported at key U.S. facilities were residents of Mexico, Brazil, Canada, Pakistan and Indonesia. Hill Air Force Base - a hub for maintenance on fighter jets, cargo airplanes and ballistic missiles, among other military hardware - is among the scores of military bases that trusts contractors to clear their own employees.

That unnerves Ira Mehlman, spokesman for the Federation for American Immigration Reform. He said the time to trust contractors is over.

"They've found all sorts of ways to game the system, including using subcontractors . . . which is a favored way of employers getting out of responsibility," Mehlman said.

Out of trouble: All nine men arrested at Dugway on Feb. 9 have since been deported, Immigration and Customs Enforcement Agent Adam Parks said last week. He said an investigation continues into the drywall company that hired the illegal workers and allowed numerous unchecked others onto the base previous to the arrests.

Employers don't always face sanctions, though.

Last March, for instance, immigration agents in Boston arrested 14 illegal workers who had been employed at - and given unfettered access to - Logan International Airport by subcontractor Hurley of America. Hurley officials denied responsibility, saying they didn't have the ability to check every employee.

Nearly a year after the arrests, the company has not been criminally charged.

A U.S. Department of Justice spokeswoman in Salt Lake City said that, with limited resources, attorneys in her office don't prosecute many employers of undocumented workers.

"We have done some but haven't done many," Melodie Rydalch said. "Part of that is resources and part of that is proving the elements of the crime."

But regardless of the outcome in the courts, if homeland security advocates have their way, the Logan response to the arrests shows what can be done to close the hole.

In the wake of the Logan case - which came 3 1/2 years after the attacks of Sept. 11, 2001, in which two airplanes from the airport were hijacked - officials finally changed the rules regarding who may issue security badges.

"We ended the practice of allowing outside contractors to issue ID badges for our airport," said Logan Communications Director Danny Levy. "We were like, 'Forget it. We'll do it ourselves.' "

She was surprised to learn that not everyone has taken similar steps.

In some places, no changes: In Oakland, officials say there hasn't been any change in the patchwork of regulations, organizations, oversight and blind trust that failed to prevent illegal workers from finding employment at a facility responsible for inspecting cargo coming into Bay Area ports - a duty homeland security experts say is crucial to protect the nation from potential threats.

And though it had been the subject of an illegal hiring practice investigation at least once before, the company that employed the Oakland undocumented workers remains in charge of vetting its own employees, said Immigration and Customs Enforcement Agent Ray Greenlee.

Greenlee noted that his agency performs checks on employees hired by such companies. But he declined to say how long it takes.

"There's a lot of work to be done out there," he said, "and we continue to do it with the staff that I have."

At least some of the men arrested in last year's Oakland sweep, he conceded, had been working at the facility for years.

Dugway officials said Thursday that they could not confirm whether they had made any changes in access policies as a result of the arrests at their base and would not say whether any such changes were intended in the future.

No jurisdiction, no champion: Immigration and Customs Enforcement officials say they don't have the authority to change security policies at hundreds of locations considered to be sites of "critical infrastructure," even if case after case shows a pattern of security holes that could largely be filled by taking the authority for granting access out of the hands of contractors and subcontractors.

"In terms of policies and procedures of those respective jurisdictions, we don't have the authority to go in and basically make changes," said Kice, the customs spokeswoman. "In terms of access, we aren't in a position to mandate how they do checks."

But those who are pushing for such changes - like Ira Mehlman, the immigration reform advocate - say they haven't yet found a champion for the cause who does have that authority - a member of Congress, for example.

mlaplante@sltrib.com