For eight hours a day, six days a week, two grieving parents stand on a South Georgia street corner with homemade signs, family photos and a question: “What Happened to Kendrick Johnson?” January 10, 2013, their 17-year-old son disappeared between classes at his Valdosta high school. The next morning, the three-sport star's body was found upside down in a rolled mat in the school's gym. Within hours of finding Johnson's body, local investigators determined his death was an accident. A state medical examiner agreed and the case was closed. The teenager's parents never believed the official story but their pleas for outside officials to investigate were ignored. CNN's Victor Blackwell was the first television correspondent outside the Johnson's small community to report the story. As other national and international news organizations began to take interest in the story, CNN continued to lead. Blackwell and CNN producer Devon Sayers literally traveled across the country searching for answers. They were the first or only team to report more than 40 major developments in the story. CNN has filed nearly two-dozen requests for open records. Despite strong resistance from local officials, CNN has exposed internal finger-pointing over withheld evidence and a compromised investigation, missing body parts and suspicious holes in school surveillance footage, which CNN successfully sued to obtain. After CNN's more than 20 reports, each offering exclusive details, the Department of Justice launched a federal investigation into Johnson's death and the sheriff's handling of the case. The Georgia Secretary of State's Office also launched an investigation into a local funeral home's treatment of Johnson's corpse. Those investigations are ongoing. Beyond reporting the details of a bizarre and emotional story, CNN's continued coverage of the circumstances surrounding the death of Kendrick Johnson fulfills a core mission of journalism: It holds those in power accountable.