Chief Tony Carleton said Tommy Ivy Jr. was stopped for a traffic infraction by Natchez Trace park rangers at 8:55 p.m. Sunday.
Ivy, who also has qualified in the Chickasaw County's sheriff's race, was later arrested and taken to the Lee County Adult Detention Center on the DUI charge. It is unknown if Ivy went through any field sobriety test.
Carleton said Ivy was immediately put on administrative leave and the case was turned over to the department's Internal Affairs division.
Carleton said Ivy will remain on paid leave until the investigation is complete and he goes to court. Then the case will be evaluated and his job status and punishment will be decided.
Ivy has been a Tupelo police officer since 1991. He is a patrol officer and one of the department's motorcycle policemen.