​Napier began his career with the department in 2004 as a correctional officer at Northpoint Training Center (NTC). Beginning in 2009, he has been promoted to sergeant, lieutenant, captain, unit administrator II, and most recently to major in 2019. As a unit administrator II, he oversaw the Restrictive Housing Unit and general population units. As major, he supervised the security operations of the prison to ensure the safety and control of the institution. 

During his tenure in Corrections, Napier has assisted with recruitment, worked as a PREA investigator, and served as a training instructor in Taser, cell entry, OC spray, pepper ball, and incident command. He served on the NTC Emergency Response Team for 10 years, including acting as the NTC and Central Regional Team commander. Additionally, Napier developed and implemented the Future Leaders Program at NTC, which assists with employee morale and retention.

Napier has been recognized many times by the department for his excellence in leadership. He was awarded Employee of the Month in 2015, Supervisor of the Year in 2011 and 2013, and Support Staff Member of the Quarter in 2019 and 2021. In both 2011 and 2013, Napier received DOC Achievement Awards. He served as the president of the Lake Herrington Chapter of KCCD 2014-2015. He is a 2014 graduate of the Commissioner's Executive Leadership Program.​