New court records in the Boston Marathon bombing case implicate Tamerlan Tsarnaev in a brutal unsolved triple murder carried out in Waltham, Massachusetts two years ago. According to federal prosecutors, Tsarnaev's friend Ibragim Todashev ratted on the deceased bombing suspect before being shot dead by the FBI in Florida. Prosecutors say if lawyers for Dzhokhar Tsarnaev obtain documents related to his older brother's role in the Waltham case, it could hurt an ongoing investigation by the Middlesex DA's office.