IOWA CITY, Iowa (AP) — Testing on a cap worn by the presumed killer of a man 45 years ago has failed to exonerate a prisoner who maintains his innocence in the fatal 1976 robbery. It’s the latest setback for lawyers hoping to prove Iowa’s first wrongful conviction based on DNA. Recent court-ordered testing found Gentric Hicks cannot be excluded as one of at least two people whose DNA is believed to be on the orange hunting cap. But the finding is inconclusive and does not rule out Hicks’ late half brother, whom a key witness initially identified as the killer, because authorities do not have his DNA on file. Hicks is serving life at the Anamosa State Penitentiary.