SAN DIEGO -- A San Diego school employee may face jail time for using a San Diego Unified School District credit card to buy personal items, including underwear and clothing, 10News reported.

Rachel Rayburn, a clerk at Horace Mann Middle School, pled guilty to grand theft charges after an investigation by SD Unified's Office of Audit and Investigations. The group found Rayburn spent nearly $6,500 on the district's and taxpayers' dime. Rayburn faces up to three years in prison and has to pay a $10,000 fine.

"This employee started using the credit card … she bought undergarments and clothes," said Andrea Niehaus, who is in charge of the group. "We saw some unusual expenditures that didn't look appropriate. As a result, we were able to prove that she was using the credit card for personal use."

Niehaus, who often goes undercover, and her group is responsible for policing what happens to citizen tax dollars. So far, Niehaus said nine employees have been fired for not following the rules.

10News obtained a copy of the items Rayburn bought, which, among other things, included food products, underwear and stockings. Rayburn frequently charged the credit card at Target and Wal-Mart.

"A lot of times it's a person that maybe puts in a lot of extra time and that they're due this money. That's how I think they rationalize it," said Niehaus.

Rayburn's case is just one of dozens SD Unified's audit group has exposed. The school district created a fraud hotline five years ago so anyone can file a report. There have been 398 complaints so far, and 307 have been resolved.

A complaint from the hotline led to the conviction of Jess Macias, a city schools maintenance supervisor who stole $27,000 over a two-year period from the recycling of metal ramps for portable classrooms.

The audit group wants to catch people like Macias and Rayburn to make sure citizen tax dollars are spent correctly.

Macias was sentenced to four months in jail and had to pay all the money back.

Rayburn will be sentenced in January.