Now we move on to the new tragedy at another american school, this time a high school in massachusetts. 48 hours after a 12-year-old shot a teacher in reno, another beloved teacher found dead,... See More
Now we move on to the new tragedy at another american school, this time a high school in massachusetts. 48 hours after a 12-year-old shot a teacher in reno, another beloved teacher found dead, murdered. This time a 14-year-old member of the soccer team is under arrest. Abc's gio benitez with the very latest. Reporter: Behind this smile, a young math teacher, just 24 years old. Colleen ritzer was nothing short of beloved. She was one of the best teachers danvers high has ever had. She really made an impact in everyone's lives. Reporter: But overnight, her body was found in the woods, near the massachusetts school she loved so much. And, this afternoon, one of her own students was charged with her murder. Police say 14-year-old philip chism stabbed ritzer in a school bathroom, and that surveillance cameras show him moving her body out to the woods. His alleged motive, still a mystery. It is the second time this week a teacher has been senselessly killed at school, allegedly at the hands of a student. Monday, 45-year-old michael landsberry, also a math teacher, was shot to death in sparks, nevada. Ms. Ritzer's final tweet to her friends was about that tragedy. "My thoughts and prayers are with those involved in the nevada middle school shooting. Simply devastating." Today, her best friend described her as overflowing with life. She didn't do crazy things to make her happy. She could find joy in anything. She brought so much joy in my life. Reporter: On twitter ritzer called herself a "math teacher often too excited about the topics I'm teaching." She was born to teach. She always loved working with kids. I think they just gravitated towards her and I think as much as they loved her she loved them 100 times more. Reporter: Chism had recently moved here from tennessee. He was on the soccer team. Last night, he missed practice and his teammates went out searching for him. What kind of person is he? We were one big family. We all knew him, liked him. He was nice. We just never saw it coming. Reporter: And that 14-year-old's mother was in court today. Her son was charged as an adult. Tonight the key question that nobody seems to have an answer for was why was that teacher killed. Thank you so much. On this note. We talked about the world series. Tonight the boston red sox observing a moment of silence for colleen ritzer.
This transcript has been automatically generated and may not be 100% accurate.