Witness whose lie helped put an innocent man in prison speaks out on "48 Hours"
Lamar Johnson, of Missouri, was exonerated in February for a murder he didn't commit. He spent almost three decades in prison. In a new "48 Hours," Erin Moriarty speaks to Greg Elking, the witness who helped put Johnson away, for his first TV interview. Moriarty joins CBS News to preview the episode, airing Saturday, April 29, at 10/9c on CBS.