Police are trying to determine whether a former marketing teacher at Lake Travis High School engaged in an improper relationship with a student during a field trip in Fort Worth.

The teacher resigned from Lake Travis High School on May 12 after being placed on administrative leave on May 5, according to Marco Alvarado, Lake Travis school district spokesman.

The Travis County district attorney's office concluded that because the incident in question allegedly occurred at a Fort Worth motel during a field trip sometime in February, Fort Worth police have jurisdiction over the investigation, said Roger Wade, Travis County Sheriff's Department spokesman.

Fort Worth police confirmed that an investigation is under way, but declined to add anything further.

The investigation began after Travis County deputies received a report from Lake Travis High School officials that a student member of DECA (Distributive Education Clubs of America) and the teacher engaged in an improper relationship after a school-sponsored event, Wade said.

The student is not listed as a juvenile, Wade said.

The teacher taught business and marketing and resigned after four years with the district, Alvarado said.