Any sheriff of Marengo County (1) who has served for 13 years as sheriff, and who becomes permanently and totally disabled, proof of such disability being made by certificate of three reputable physicians, or (2) who has served a minimum of 16 years as sheriff and who has reached the age of 52 years may elect to become a Supernumerary Sheriff of Marengo County by filing a written declaration to that effect with the Governor. If the Governor shall find any such declarant qualified under either subdivision (1) or subdivision (2), a commission as Supernumerary Sheriff of Marengo County shall thereupon be issued to such declarant by the Governor.