Prosecutors said in court that Chism beat Ritzer to death.
A court filing said Ritzer and Chism were known to each other from the high school, but it did not elaborate. The arrest was made based on statements by the suspect and corroborating evidence at multiple scenes, investigators said in court documents.
Ritzer's family said they are mourning the death of their "amazing, beautiful daughter and sister."
"Everyone that knew and loved Colleen knew of her passion for teaching and how she mentored each and every one of her students," the family said in a statement provided by her uncle Dale Webster.
At his arraignment in adult court, Chism's defense attorney argued for the proceeding to be closed and her client to be allowed to stay hidden because of his age. The judge denied the request. The lawyer, Denise Regan, declined to comment outside court.
The tall, lanky teenager had moved to Massachusetts from Tennessee before the start of the school year and was a top scorer on the school's junior varsity soccer team, said Kyle Cahill, a junior who also plays soccer. He said the team had been wondering where Chism was when he skipped a team dinner Tuesday night.
"We're all just a family. It just amazes me really," Cahill said. "He wasn't violent at all. He was really the opposite of aggressive."
Ryan Kelleher, a senior, said students related to the young teacher, who liked to wear jeans and UGG boots just like the teenagers she taught. Kelleher, who also plays soccer, said the arrest of the soft-spoken Chism didn't make sense to him.
All public schools in Danvers, about 20 miles (30 kilometers)north of Boston, were closed Wednesday.
Ritzer is the second teacher allegedly killed by a student in the U.S. this week. A Sparks, Nevada, middle school teacher was allegedly shot by a 12-year-old student on Monday.
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Associated Press writer Lynne Tuohy in Andover and news researcher Rhonda Shafner in New York City contributed to this report.