BUCYRUS — A judge in northern Ohio has turned down a one-time death row inmate’s request for a new trial based on concerns that have surfaced around a former state crime lab worker. Attorneys for Kevin Keith made the request and questioned whether the state forensic expert provided unreliable testimony against him at his 1994 trial. The forensic expert who worked then for Ohio’s Bureau of Criminal Investigation has denied manipulating evidence. But the state public defender and others have formed a task force to review cases involving the longtime forensic scientist whose credibility has been questioned. A Crawford County judge last week rejected Keith’s bid for a new trial. Keith was convicted of killing three people in Bucyrus in 1994.