Ever since Carol was sent into exile for executing Karen and David, I've had my doubts that she was really the person responsible for the killings. One theory that has been floating around is that Lizzie was the murderer and Carol was covering up for her crimes.
After shooting Tara's girlfriend in the The Walking Dead mid-season finale Lizzie proved that she's not afraid to shoot somebody in the face and now showrunner has revealed that scene has wider implications for Carol's storyline:
I like to say that scene, however sensational it is in the moment, was there to serve that Carol story. We’ll be addressing that in the future. It's all part of a greater story. It’s important to know that that wasn't just some big sensational moment.
Who do you think is responsible for Karen and David's murder?