The Maricopa County Sheriff’s Office (MCSO), established in 1871, serves as the primary law enforcement agency for Maricopa County, Arizona—the fourth most populous county in the United States. Headquartered in Phoenix, MCSO employs approximately 2,850 personnel and operates with a budget of $526 million as of 2024. The agency provides patrol services, criminal investigations, and operates the county jail system, serving both unincorporated areas and several contract cities within the county