JEFFERSON CITY, Mo. (AP) – Missouri Attorney General Chris Koster has won a second term after beating the chief of staff to a former Republican governor.Koster’s victory Tuesday keeps the attorney general’s office under Democratic control for another four years. Missouri has had a Democratic attorney general since 1993. Koster is a former state senator and Cass County prosecutor. He left the Republican Party to become a Democrat in 2007.Republican attorney general candidate Ed Martin sought to tie Koster to President Barack Obama, calling him “Obama’s lawyer.” Martin served as the chief of staff to Republican former Gov. Matt Blunt.