Vacancies in the Fairfax County Sheriff’s Office have grown sixfold in two years, a trend officials say is responsible for ballooning overtime pay and strained jail and courthouse staffing, according to a report by county auditors.

The shortage has forced Virginia’s largest Sheriff’s Office to scale back services at the county’s Adult Detention Center in downtown Fairfax City, curtailing family visits and physical exercise while confining inmates to their cells, Sheriff Stan Barry said.