An accountant for the Nifty Fifty's restaurant chain has been indicted in a tax-evasion scheme that federal prosecutors say hid millions of dollars from the Internal Revenue Service.

An indictment unsealed today charges 58-year-old William J. Frio, of Springfield Township, with conspiracy, filing false returns, loan fraud, and aggravated structuring of financial transactions.

Prosecutors say Frio, who has been providing accounting services to Nifty Fifty's since 1986, conspired with the popular chain's owners in a scheme that used skimmed cash to help themselves and associates avoid paying taxes.

The chain's owners were indicted in May 2012 and sentenced in November. The 1950s-themed restaurant chain has four locations in Pennsylvania and New Jersey.

Frio prepared income tax returns for Nifty Fifty's and individuals that concealed more than $15.6 million from the IRS, evading employment and personal tax payments of more than $2.2 million, the indictment alleges.

Frio also submitted a false loan application in 2008 for a mortgage for his personal residence, submitting fake tax returns and W-2 forms, prosecutors said.

He also allegedly used his role as Nifty Fifty's accountant to embezzle hundreds of thousands of dollars from the organization.