A sister stands by the brother accused of murdering their parents. She insists that he's innocent and there's more to the story. "48 Hours" correspondent Erin Moriarty reports.

Has a forensic document expert unmasked the anonymous author of the infamous Circleville letters? For nearly two decades, an anonymous letter writer terrorized the small town of Circleville, Ohio, by sending threatening letters that exposed alleged secrets about neighbors and friends. Erin Moriarty and 48 HOURS investigate the true crime mystery behind the letters and interview experts about the documents.