Police found blood in a bathroom on the second floor of the school before recovering Ritzer's body in the woods behind the school. She was reported missing late on Tuesday after she failed to return home and did not attend phone calls.
Chism is a soccer player at the school. Police arrested him after recovering evidence at several places and the video surveillance. It remained unknown how and why he killed the teacher.
It was the second murder case this week involving teen students in the US schools. A 12-year-old student fatally shot a maths teacher on Monday at the Sparks Middle School in Reno city in the US state of Nevada.