He was initially assigned as a Vocational-Landscape Gardening Instructor at California State Prison-Los Angeles County (LAC) in 1993.
At LAC he held many positions, such as Supervisor of Vocational Instruction and Correctional Plant Supervisor.
Howell transferred to the California Correctional Institution in 2001 as a Correctional Plant Supervisor. In 2009, he promoted to Correctional Plant Manager II.
Later in 2009, he promoted to Correctional Business Manager II at WSP-RC. in 2013, he promoted again to Associate Warden.