RIVERSIDE (AP) — A man who was wrongly convicted of a 1998 murder in Southern California and spent two decades in prison has filed a federal lawsuit. Horace Roberts on Tuesday sued Riverside County and officers from its Sheriff's Department, alleging they failed to turn over exculpatory evidence to prosecutors. Roberts was wrongly convicted of the murder of Terry Cheek and sentenced to 15 years to life. Roberts' lawyers say he was freed last year after conducting his own DNA testing of crime scene evidence and new arrests were made in the case. The 61-year-old Roberts says in a statement he can't get back lost time but hopes for reforms to help prevent future injustice. A message seeking comment was sent to the Riverside County Sheriff's Department.