Elected from jail, DC official advances voting rights and racial justice

The election of a D.C. inmate to local government is pushing the boundaries of voting rights and racial justice.

After nearly three decades behind bars, Joel Caston is seeking redemption through politics. The 44-year-old felon, convicted of murder as a teenager, became the newest elected public servant in Washington, D.C., this summer, winning a groundbreaking election for neighborhood commissioner on the city's southeast side. "It sounds great to have an official title, I must admit that. However, what it feels like is that now I have to deliver," Caston told ABC News in an exclusive cell block interview inside D.C. jail. "My constituents spoke by way of voting, and how I have to do great as I promised in my campaign." WATCH: Campaigning and voting from inside prison. Tonight on ABC News Live Prime 7p/9p ET; Sunday on This Week 9a ET.