Jury members are typically highly capable of reasoning and understanding as they are carefully chosen from a large pool of candidates. They tend to be highly educated professionals (for many reasons, not just because lawyers choose them) who just also happen to not closely follow news, politics, or be chronically online. They likely know about some guy killed a healthcare CEO a few months ago, but there knowledge of the situation is only surface level and not influenced by media biases. This makes them best able to form rational conclusions as a result of the trial.