PROVO — Police have cracked a counterfeiting ring that officials say produced almost flawless identification cards for illegal immigrants.

Immigration and Customs Enforcement, the Utah County Major Crimes Task Force, Provo police and U.S. postal inspectors arrested four men Tuesday in connection with the manufacture of false social security cards, drivers' licenses and green cards.

"These are the best documents in 15 years of law enforcement I have ever seen," said Major Crimes Task Force Lt. Mike Forshee. "They're good. They are high-quality good."

The four men, all Mexican nationals, were allegedly caught printing documents when officers served a search warrant at three homes, each serving as a production hub, Forshee said. The men were booked into the Utah County Jail.

Officers also confiscated computers, scanners, printers and laminators used to produce the fraudulent documents.

"It's the largest (counterfeit bust) I've seen," Forshee said. "Most certainly the best documents I've seen in Utah County."

Although officials aren't sure how long the group has been producing the materials, Forshee said the men have been mailing the cards to other states. He estimated they could have produced around 50 cards a week.

Postal inspectors were also called to assist in the probe because the inspectors — who are also federal agents — deal with any crime involving the post office, said Salt Lake City-based agent Bob Maes.

"(We have) ways of getting information," Maes said, "(but) we always follow the proper legal channels. To open any mail, a federal search warrant is required. We don't go through and open mail willy-nilly. It takes a lot more, just as entering a home, going into a vehicle — search warrants are required and the burden of proof is required."

"They were actually receiving photographs and money from other states to do these and ship them back out, so to us that's a huge threat," Forshee said. "It's a Homeland Security issue to us."

The nearly monthlong investigation began with one of ICE's routine business visits to check for proper employee documentation. Three people in one business had similar cards that officers were able to track back to one source.

While the cards were almost flawless, some details, such as specific numbers, didn't escape the trained officers.

The three individuals with the cards were in the country illegally and are also being detained, Forshee said.

While the Hispanic community does not condone such behavior, it happens all the time, said Tony Yapias, project coordinator for Proyecto Latino de Utah.