This just keeps getting worse. Sources close to the investigation tell CNN that Philip Chism, the 14-year-old student charged in the murder of his high school teacher, Colleen Ritzer, used a box cutter which he bought and then brought to school to kill her. Described as a “quiet young man,” the star athlete allegedly killed Ritzer in a school bathroom before rolling her body outside in a recycling bin and leaving her in the woods. Police are still searching for a motive. Chism says he is not guilty of the grisly murder.