Federal and state agents are investigating the possibility that illegal immigrant workers have been living in the walls of a new medical center in Florida, MyFoxOrlando reported Wednesday.

Authorities combed the construction site of the new multimillion dollar VA Medical center in Lake Nona’s Medical City with thermal imaging devices in the second raid within a 24-hour period.

"We didn't see anything," worker Anthony Willis told MyFoxOrlando, "just told us to come out of our work areas and have our IDs ready."

After the warning, law enforcement officers descended on the site.

"All of a sudden cops come around with the four-wheelers," Shon Trusdale, a steelworker, said. "Next thing you know, a helicopter is up here and guards at the gates."

A source involved with the investigation confirmed that authorities were looking for illegal workers who are using fake Social Security cards. There were few details offered by investigators by mid-afternoon and it was not entirely clear which law enforcement agencies or how many agencies were involved in the raid.

"There is an ongoing investigation into the employment practices of some of the subcontractors who are the site here doing construction," Major Geoffrey Branch with the Florida Department of Financial Services Division of Insurance Fraud said.

The head of the project said that he knew the raid was coming and cooperated with authorities, handing over payroll records and other documents. The VA says it checks a worker's status using Florida's E-verify system.

"The contractors are required to submit Social Security numbers of their employees. It's something our contract requires. That's the primary check that we use," Bart Bruchok, a senior engineer, said.

"You've got to have papers just to get on the site," subcontractor Jake Drost said, "OHSA licenses and everything to be able to work on it, so I don't know how someone gets through the cracks like that."

However, other subcontractors told MyFoxOrlando that it's not difficult for illegals to buy bogus paperwork and get on the job, something echoed by site workers.

"I know of a guy who got deported," Trusdale said. "A week later, he was back with a different name."

An Orange County Corrections pulled out of the construction site, but it was unclear how many workers, if any, may have been taken into custody.

Work is expected to resume Thursday.

Almost 1,000 people work on the construction site daily and that number is expected to double in the next couple of months. The 1.2-million square foot facility, opening in fall of 2012, will cost $665 million to construct. The medical center will have a large multispecialty outpatient clinic, 134-inpatient beds, 120-community living center beds, a 60-bed domiciliary and administrative and support services. 

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