Prosecutors say Mark Chiles pleaded no contest to the misdemeanor shoplifting charge. He was found guilty Monday by a Mesa Municipal Court judge and fined $300.
Chiles was cited April 3 by Mesa police on the shoplifting charge stemming from the theft of a $40 speaker from a store on March 28.
Chiles took a leave of absence after the presiding judge of the Maricopa County Justice Courts learned about the shoplifting incident from The Arizona Republic.
Chiles cited medical problems when he resigned from his $101,500 a year job effective May 31.
Ex-county assessor Keith Russell was appointed by the Board of Supervisors to replace Chiles.