DES MOINES, Iowa (AP) — The superintendent of Iowa’s largest school district, who was detained last week by immigration agents, was charged Thursday in federal court with possessing firearms while in the U.S. illegally, prosecutors said. Officials said he was taken into custody on a federal arrest warrant for the weapons charge and appeared by video before a federal magistrate judge. Roberts’ attorney, Alfredo Parrish, said his client will plead not guilty. Federal authorities said Roberts had a final removal order that was issued last year, and an immigration judge denied a motion to reopen Roberts’ immigration case in April this year. Roberts had been under the impression from a prior attorney that his immigration case was “resolved successfully,” his attorney has said.