Commander Billy Duke joined the San Diego County Sheriff's Department in December 1997 and graduated from the 30th Corrections Academy in February of 1998. He was assigned to the George Bailey Detention Facility (GBDF) where he spent time as a line deputy, the facility operations deputy, a training officer and corporal. In March of 2003, Billy was promoted to the rank of sergeant and assigned to the San Diego Central Jail (SDCJ) where he was a team sergeant, the facility training sergeant, and the facility administrative sergeant. In 2005 he was transferred to work for the Sheriff's Internal Affairs (IA) Unit.

In 2006, he was promoted to the rank of lieutenant and assigned to the Las Colinas Detention Facility. In 2009 he was assigned to the Detention Training Unit. In 2011 he was assigned as the lieutenant for the Detention Support Division. In October 2011, he was promoted to the rank of Captain. As a Captain Billy was assigned to the Detention Support Division and then the East Mesa Detention Facility where he managed the project to increase the facility capacity by 400 beds and transform the facility to a male reentry facility. In 2014, he was transferred on special assignment to the San Diego County Probation Department where he oversaw all juvenile institutions operations as the Deputy Chief.

After 18 months, Billy returned to the Sheriff's Department and was assigned as the facility commander at the George Bailey Detention Facility. In 2018, he was transferred to the San Diego Central Jail and then to the Medical Services Division shortly thereafter.

In December of 2020, Billy was promoted to the rank of Commander and assigned to manage Area 1 of the Detention Services Bureau. Billy holds a bachelor's degree in the Administration of Justice and lives with his family in South County.