12 plead guilty to tax and immigration charges.

Twelve people across seven construction-related companies have pleaded guilty to charges related to employment tax fraud and hiring unauthorized aliens in what acting U.S. Attorney M. Rhett DeHart called the largest criminal Internal Revenue Service operation ever in the Pee Dee region.

The pleas are the first to come from a multi-year undercover investigation in the Myrtle Beach area and throughout the S.C. coast led by the IRS and Homeland Security Investigations, according to a news release from the district office of the U.S. attorney.

The operation targeted those in the construction industry who used unlicensed check cashers to facilitate under-the-table cash payments to employees, many of whom were living in the country illegally, the news release said.

The government also says the check cashers would provide certificates of insurance falsely stating that the employees were covered under workers' compensation insurance. These off-the-book payments defrauded the United States out of applicable employment taxes on the employees, investigators said.

Each of the 12 defendants pleaded guilty to one felony count of conspiracy to defraud the United States and one misdemeanor count of unlawful employment of aliens. At least $15 million in checks were cashed by these defendants, resulting in millions of dollars of total losses to the government. Based on the investigation, the U.S. attorney's office says at least "tens of millions" of dollars of tax losses have occurred throughout the S.C. coast because of similar schemes.

"Those who steal from the government, and by extension the American taxpayers, will not find refuge in South Carolina," DeHart said in the release. "By evading millions of dollars in taxes and falsely claiming their workers had insurance, these defendants made it harder for honest business owners to compete in the construction industry along South Carolina's coast and they left their workers exposed to injury without insurance. I want to thank the IRS and HSI for their tireless efforts, as well as our local partners who assisted during this operation. We will continue to prosecute businesses and individuals who try to get ahead by breaking the law."

Evidence presented to the court said that beginning around late 2018, IRS and HSI began jointly investigating the practice of illegal check cashing within the construction industry in the Myrtle Beach area and in other regions along the coast.

Specifically, certain construction...