A 61-year-old San Antonio businessman pleaded guilty Thursday morning to his role in what is believed to be the largest real dollar loss fraud-and-tax-related case ever prosecuted in the Western District of Texas, according to U.S. attorneys.

Larry W. Kimes, the manager of AccounTex Financial Services, LLC, pleaded guilty to a Klein tax fraud conspiracy charge and a mail fraud conspiracy charge.

Kimes admitted to authorities that between 2002 and 2008 he and other co-conspirators stole more than $133 million from the clients of a series of Professional Employer Organizations that he and co-defendant Charles Pircher operated.

The PEOs controlled by Kimes and Pircher, which included Service Professionals, entered into staff leasing agreements with various client companies to manage the companies' payroll and insurance programs, authorities said.

Kimes and co-conspirators diverted to their own use and benefit clients' monies that U.S. attorneys said should have been paid for payroll taxes and insurance premiums.

Official said Kimes faces up to 20 years in federal prison on the mail fraud conspiracy charge and up to five years in federal prison on the Klein tax fraud conspiracy charge.

"This guilty plea brings to justice the six perpetrators of a scheme that stole over $133 million from clients and taxpayers," said U.S. attorney Robert Pitman. "The defendants, including Kimes, managed to conceal their crimes behind the complexity of the scheme. Through the hard work of FBI, and IRS-CI agents and Tom McHugh in this office, the defendants' crimes have been revealed and they will be held accountable."

Kimes also agreed that full restitution in this case amounts to $133,401,713, according to U.S. attorneys. Sentencing has yet to be scheduled.

Kimes' co-defendants -- Pircher, John D. Walker II, John Bean, Mike Solis and Pat Mire -- are all scheduled to be sentenced on Feb. 21.