PHILADELPHIA (AP) —The founder of a Philadelphia cheesesteak restaurant and one of his sons have pleaded guilty in a federal tax fraud case alleging the hiding of nearly $8 million in sales over the course of a decade.

The Philadelphia Inquirer reports that 83-year-old Anthony Lucidonio Sr. and 55-year-old Nicholas Lucidonio, two owners of the well-known cheesesteak and sandwich shop Tony Luke’s, pleaded guilty Monday to conspiring to defraud the U.S. government.

The New Jersey residents told a federal judge that they kept two sets of books to hide cash from sales at their south Philadelphia shop and acknowledged paying part of workers’ salaries under the table to evade payroll taxes, the newspaper reported.

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The defendants, who are to be sentenced later this year, said in a statement released by their attorneys that they “accept full responsibility for paying some Tony Luke’s employees in cash. This practice ended in 2017, over five years ago.”

The statement said the defendants “have fully cooperated with the government’s investigation since it began and look forward to putting this matter behind them.” Tony Luke’s, they said, “will continue to serve its faithful clientele and provide gainful employment for its loyal employees and their families.”

The face of Tony Luke’s, Anthony Lucidonio Jr., known as Tony Luke Jr., was not named in the indictment. He split from his father and brother in 2015, followed by a public sometimes personal court battle over franchising agreements and recipe ownership.

Tony Luke’s opened in 1992 and now has more than a dozen locations in Pennsylvania, New Jersey, Washington D.C., Maryland, Texas, and Bahrain.