GRAND PRAIRIE, Texas – Former Grand Prairie Independent School District CFO Carolyn Foster faces up to a decade in prison for allegedly swindling $600,000 from taxpayers.

Foster, 61, was arrested by the Secret Service on Monday at the International Leadership of Texas, where she’s worked since retiring from Grand Prairie schools last August, WFAA reports.

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The day after Foster left the district, two accountants reviewed school finance records and allegedly found she mishandled district funds by ordering cash deliveries in armored trucks to the district’s vault, money she claimed was for teacher awards, school supply reimbursements and payouts for lawsuits that did not exist.

“I could not be more proud of the employees who immediately caught some discrepancies,” GPISD Superintendent Susan Hull said. “Once they had the data the records back in their control, and they could see everything, they immediately caught some discrepancies that caused them to think there could be fraud or there could be theft.”

Hull said Foster “abused her authority as CFO” to manipulate cash handling rules and gain access to the vault in the administration building, where she allegedly took $600,000 in cash between October 2014 and July 2015, according to Kera News.

“What that former official, Carolyn Foster, is charged with doing is a reprehensible act of selfishness and greed, and we are working with authorities to prosecute her to the fullest extent of the law. It is unconscionable that someone serving in a position of authority for an organization responsible for educating and nurturing the children of our community would violate that sacred trust,” Hull wrote in a letter to parents.

“We are working with the authorities to retrieve every penny that was taken, and we have new procedures in place to make sure no one can commit such an act again. I also ordered an independent audit of these funds to determine whether any other funds are missing, if other district employees or others may have been involved in the theft, and to assist in establishing any other needed processes and procedures.”

Hall said the district has already implemented new controls to ensure “never again can a single person, even a high-ranking executive, on his or her own authority gain access to money that belongs to our schools,” according to the Dallas Morning News.

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Foster, who was paid $149,500 a year as district CFO, now faces up to 10 years in prison and a $250,000 fine if convicted. She pleaded not guilty in an initial court appearance Monday before U.S. Magistrate Judge David L Horan and was released on bond, the news site reports.

Officials at International Leadership Academy said Foster was hired in April on a contractual basis to help the school transition to a new finance software. She was fired when the district learned of her pending theft charge, spokeswoman Brittany Taylor told the Morning News.

“We were completely unaware of her previous circumstances,” Taylor said.

Assistant U.S. Attorney Aaron Wiley, who charged Foster with a single count of federal program theft, said the case is among the worst he seen.

“Most cases we come across involve people taking someone’s identity or fraud where some money is taken, but those cases always involve paper trails,” Wiley said.

“But this case, it’s just the boldness of it,” he said. “It’s staggering.”