By HANNAH FINGERHUT and RYAN J. FOLEY, Associated PressDES MOINES, Iowa (AP) — The Des Moines public schools chief who’s been detained by immigration authorities resigned his position Tuesday while he challenges his potential deportation, his lawyer said. Former Superintendent Ian Roberts had been under the impression from a prior attorney that his immigration case was “resolved successfully,” said attorney Alfredo Parrish. “I am writing to inform you of the closure of your immigration case. Norris said the Des Moines district had not been notified of the ruling until it received a copy on Monday. He paid both of the Iowa tickets in cash.