Sgt. Hainley has been a police officer with the Enid Police Department since 2014. He served as an FTO until he was promoted to the rank of Sergeant in 2020. He is presently assigned as both a Patrol Sergeant in the Uniformed Services Division as well as the Communications Sergeant in the Support Services Division. His additional duties include maintaining all Intoxilyzer 8000 certifications within the department, ensuring new officers get sent to Intoxilyzer training, and maintaining and calibrating all department portable breath tests. Sgt. Hainley is also currently spearheading the development of a new training program for the Enid/Garfield/Major County 911 Center.

Sgt. Hainley was nationally certified as a Drug Recognition Expert in 2017 and as a DRE Instructor in 2022. He been very active in the DRE training program, teaching multiple DRE schools, ARIDE courses, refreshers, and has taught every SFST basic course at the Enid Police Academy since its inception. Sgt. Hainley was appointed by the DRE State Coordinator as The Northwest Region Coordinator in July 2024.