Mark DeSimone was a member of the Arizona House of Representatives for a single term. He represented the 11th District during the 48th Legislature, winning the November 2006 election. He was unsuccessful in his bid for re-election in 2008.In June, 2019, DeSimone was sentenced to 65 years' imprisonment for the 2016 first-degree murder of his friend, Duilio Antonio "Tony" Rosales, during a vacation in Alaska. In what DeSimone claimed was an accident, Rosales was shot twice in the back of the head.