Prosecutors have spent the last month presenting some haunting evidence against admitted Boston Marathon bomber Dzhokhar Tsarnaev, which seems to go beyond what the government needs to do to convict him and begins to build the case that he should be sentenced to death. Boeri and Cullen discuss Day 15 of the trial, in which the government called its final witness to tell the jury of the horrific death of 8-year-old Martin Richard near the finish line.