DALLAS (CBSDFW.COM) – The superintendent one of Dallas’ oldest and largest charter schools stepped down Tuesday, four days after the school released financial records to the CBS 11 News I-Team.

Laura Mimms’ resignation from A.W. Brown Leadership Academies comes after the publically 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.

In an email to parents on Wednesday, Mimms wrote she is resigning “due to personal and medical reasons.”

In Mimms’ two years on the job, the district’s enrollment dropped and the school failed to meet the state standard for student achievement receiving an ‘F’ grade by the Texas Education Agency.

While student performance has remained low, records show spending by the school’s top officials has been anything but.

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.

Her credit card statements from the past two years also show dozens of charges to Southwest Airlines and valet parking at Dallas’ Love Field Airport.

On her March 2017 statement alone, Mimms had more than $3,182 in Southwest Airlines charges, a $3,580 charge at Pappadeaux Seafood Kitchen in Dallas and $4,744 worth of charges at hotels; including a $2,678 charge from the Ritz Carlton in San Francisco.

The I-Team asked the school for explanations of the charges as well as itemized receipts for all school travel. The school, so far, has not provided either.

When the I-Team asked Board President George Collins Wednesday evening whether the travel charges were all school related, he said, “I wouldn’t have the slightest idea.”

Last month, after the school board called an emergency meeting to discuss spending, the board changed the school’s credit card policy. Collins told the I-Team the changes to the policy was for better accountability.

State records show Mimms’ salary last school year was $315,000 – a more than $75,000 increase from her first year on the job.

Last year the board extended Mimms’ employment contract through 2021.

The I-Team reached Mimms by phone Wednesday but the former superintendent declined to talk on the record.

Nearly 90 percent of students enrolled at A.W. Brown Academies are economically disadvantaged, according to a state report.

For the 2016-17 school year, according to state education records, A.W. Brown Academies received more than $19 million in state and federal tax dollars.