believe the three men in prison are guilty? >> no, ma'am. they're 100% innocent. we needed someone to hate to survive because our child was dead. >> reporter: we meet him at the super max prison, an hour's drive south of little rock. you were asked at the trial did you kill christopher buyers, your answer was then. >> no. absolutely not. >> reporter: your answer is. >> absolutely not. even though it's 20 years you don't get used to being asked that. it's the kind of thing that screws with your head for the rest of your life. >> we'll have deborah feyerick's full report tomorrow on 360. up next, the story that really just breaks your heart. a mom, stepfather and the little boy they lost to bullying. they say bullying that they warned the school about and got no action. later, how is michael j. fox doing nearly 20 years after being diagnosed with parkinson's? sanjay gupta sat down with him