DALLAS (CBSDFW.COM)A week after resigning, the former superintendent of one of Dallas’ largest and oldest charter schools returned to defend her name as well as her use of school funds.

During the public comment portion of Tuesday’s A.W. Brown Leadership Academies school board meeting, Laura Mimms spoke publicly for the first time since her resignation.

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Laura Mimms (CBS11)

Mimms said she never misused school funds and all credit card travel expenditures were for school related trips and approved by the Board.

Towards the end of the nearly five-hour long meeting, the Board voted to conduct an internal financial audit and placed the school’s CFO, James Montfort, on paid administrative leave.

Board President George Collins said the school is also doing away with credit cards for school officials.

Collins said many of the school’s travel expenditures, including stays at the luxury hotel Ritz Carlton, “may look extravagant but it was not.”

The Texas Education Agency told the CBS 11 I-Team it is currently investigating A.W. Brown Academies. The state agency would not comment further because it’s an open investigation.

Mimms’ resignation came four days after the publicly-funded charter school turned over to CBS 11 credit card statements from the school’s top officials in response to the I-Team’s public open records requests.

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Monthly statements from Mimm’s school issued credit card show trips to Atlanta, Washington D.C., San Antonio and San Francisco, with stays at high-end hotels and dining at expensive restaurants.

But the former superintendent said her resignation had nothing to do with the disclosure of her spending, rather it was the result of a “hostile work environment.”

In July, Mimms sent the Board of Directors a 146-page complaint outlining her concerns but she since then the environment has become even more hostile.

“It pains me that after two years of 12-hour days and great sacrifices, I had to leave the district to be able to call out wrongdoing that has been allowed to stand,” Mimms said in her public statement.

During her two years as superintendent, Mimms said A.W. Brown Academies made significant academic gains.

On the Texas Education Agency’s latest school report card, the charter school district received a “B” grade for school progress, an “F” grade for student achievement, and a “C” grade for overall performance.

Mimms said she made great sacrifices for the school during her tenure even voluntarily giving up nearly $50,000 of her salary to save a teacher’s job.

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Wednesday night, Mimms walked away from the board calling on it to do the right thing.