Assistant Superintendent of Administrative Services Bob Thomas said officials "opened an investigation and reported this information to the Tennessee Office of the Comptroller."
State officials declined to comment.
School spokesperson Melissa Ogden said Dickl was placed on administrative leave with pay Thursday.
A source told WBIR 10News that the investigation is tied to the possible personal use of two $500 gift cards that were given to food services. In addition, the state is looking into ties that a school vendor has to a car dealership that possible sold Dickl a deeply discount vehicle.
Dickl, who was hired in the fall of 2010, makes $100,800 annually.