Captain Guyovich's career with the Sheriff's Department began in June 1989, as an off-the-streeter working at Mira Loma Detention Center. She attended the Department's Training Academy and graduated as a Deputy Sheriff in December 1989. She worked assignments at North County Correctional Facility, Lennox Station, and Narcotics Bureau.

In 2000, she was promoted to Sergeant and served at Lakewood Station and Administrative Services Division as the Department's liaison to the Board of Supervisors. Upon her promotion to Lieutenant in 2004, Captain Guyovich was assigned to Lakewood Station, where she performed the duties of watch commander; Personnel Administration Bureau, where she served as the Operations and Background Investigations Lieutenant; and Administrative Services Division, where she served as Chief's Aide.