Va. Code Ann. § 52-11.2

When a county or city merges or consolidates into a city, or when a combination of counties and cities merge into a city, or when any county and all of the incorporated towns located entirely therein merge, consolidate or be annexed or when any county or part thereof be annexed into a city or cities, the governing body of any such city may thereafter request of the Superintendent of State Police, and upon such request he shall grant, the services of the Department of State Police in those areas of the counties which were merged, or consolidated or annexed into such city or cities for a period of ten years after the effective date of such merger, consolidation or annexation which were not previously incorporated.