The Sheriff Cruiser shares the chassis of the Police Cruiser (based on a combination of Ford Crown Victoria's), albeit with an LED light bar in place of the Police Cruiser's standard police lights, and Los Santos County Sheriff's livery rather than that of the LSPD.
The Sheriff Cruiser is called out when a crime is commited in Blaine County; in the city of Los Santos the Cruiser is called out at a 4-star wanted level with Noose Officers driving it. The Sheriff's Cruiser's livery is loosely based on the livery of Los Angeles County Sheriff's Department, but with all-white livery. Two emergency light bars can be fitted, an LED one similar to what is seen on the Vapid Interceptor, and a rotating incandescent one as seen in many screenshots.
NOOSE Officers can be seen driving it in the Screenshots.