The phrase "elected sheriff" means that a person is chosen by the public through voting to be in charge of law enforcement in a particular area. Full definition
He moved through the ranks to be elected sheriff in 2005. (newsday.com)
They reluctantly pick up Chris Mannix (Walton Goggins), who claims to be the newly elected sheriff of the nearby town but whose Confederate sympathies and lineage make the two bounty hunters uneasy. (artsbham.com)
Campbell was first elected sheriff in 1989 after retiring from the New York State Police. (wamc.org)