JACKSONVILLE, Fla. -- Just because the long-delayed new Duval County Courthouse is finally under construction doesn't mean all the controversy is behind the project.

One of the selling points to build the new $350 million courthouse was to create jobs for the city, but it was expected those jobs would be American workers -- not illegal immigrants.

So city workers said they were shocked when they learned Monday that out of 350 construction workers hired at the courthouse, 100 of them had falsified green cards.

That does not sit well with Kelly McMullen.

"I've been looking for a job since March, February of this year and I can't get any work anywhere," McMullen said.

Hiring undocumented workers could be a major problem for the contractors building the courthouse.

"Our primary concern is to make sure everyone who is working is doing so legally, so we have asked the General Council's Office to examine all of the facts involved, all of the laws involved and any contract provision to determine how best we should move forward," said Misty Skipper, spokeswoman for Mayor John Peyton.

The city has sent a letter to the general contractor, Turner Construction, saying, "knowingly hiring illegal workers could include contract termination." The city says the work badges of all the 100 illegal workers must be revoked, and failure to do so would be a breach of contract.

Federal Immigration and Custom Enforcement officials have been watching the construction site and have picked up 19 illegal workers near the courthouse since September.

The U.S. Border patrol told Channel 4's Jim Piggott that they are not legally allowed on the construction site, so the city has required the contractor to keep extensive records of employees, including green cards of anyone not a citizen of the United States. A review of those records on Monday revealed that scores of immigrant workers did not have proper documentation.

The city said they will be watching even closer in the future.

"Our concern is that there are people working on a city job site ... not doing so legally," Skipper said.