major developments this week in a case that cnn has been digging into for more than six months now. a u.s. attorney announced that he is launching a federal investigation into the death of 17-year-old kendrick johnson. johnson was found dead inside a rolled up gym mat at his high school in valdosta high school in january. an official said johnson suffocated after falling into the gym mat while reaching for his shoe. but his parents believe he was murdered. cnn's victor blackwell has been on top of the story. i asked him how federal investigators plan to move forward. >> the u.s. attorney says it's a combination, a review and an investigation. so he and the fbi, we'll be looking at the original investigation from local authorities. but also they're going to go out and conduct their own interviews. i spoke with a former fbi special agent. and he says they're going to treat this like a cold case in many ways, going out trying to fi find the people who were in the gym, around that gym and knew