and it's not always right. >> cullen tracked down the first eyewitness who had identified malcolm and de'marchoe as the killers. >> and he couldn't even look me in the eye. he said, man, i've been carrying around a burden. man, those boys didn't do that. >> the man told cullen he shot at the drive-by car as it sped away and claimed that detectives threatened to put him behind bars for firing his weapon if he didn't testify against malcolm and de'marchoe. >> he says that they told him he could be charged with felony murder for firing that gun and that it might have been him that killed karen summers, who knows? >> now that he was making progress, cullen needed help. so he turned to someone who's been a champion against wrongful convictions for years. tiffany murphy, then the director of the oklahoma innocence project. it wasn't the first time a tulsa case had landed on murphy's desk.