DANVERS, Mass. -- She had a bright smile, a penchant for pink and an admitted overenthusiasm for the subjects she taught. The lanky boy was just a decade younger, new to the school, with a pleasant manner but little to say.
Sometime on their last day at the school together Tuesday, prosecutors say, teacher Colleen Ritzer and 14-year-old student Philip Chism crossed paths, and he killed her.
Ritzer's body was later found in the woods behind Danvers High School, where she taught and Chism attended classes. And on Wednesday, Chism was being held without bail after being arraigned on a murder charge.
Ryan Kelleher, who had Ritzer for algebra and played soccer with Chism, said none of it made sense.
"From what I know about him and seeing him every day, it just doesn't add up that he would do such a thing, unless this was all an act to fool somebody," said Kelleher, 17.
Officials haven't released a cause of death or discussed a motive in the killing. A court filing said Ritzer and Chism knew each other from the high school, but it didn't elaborate.
Blood found in a second-floor school bathroom helped lead investigators to Ritzer's body, after she was reported missing Tuesday, Essex District Attorney Jonathan Blodgett said.
Investigators said in court documents that the arrest was made based on statements by the suspect, evidence from school surveillance cameras and corroborating evidence in multiple places.
Chism's family and attorney did not comment Wednesday.
Chism 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."
The Boston Red Sox held a moment of silence for Ritzer on Wednesday at Fenway Park before Game 1 of the World Series.
Hundreds of people later turned out for a candlelight vigil at the school parking lot, many wearing pink sweatshirts, bows or T-shirts in tribute to Ritzer and her favorite color.
"She supported all of us. We should be there to support her," said Danvers senior Courtney Arnoldy, 18, who had Ritzer for a teacher.
Ritzer, 24, lived at home with her 20-year-old brother and her sister, a high school senior.
Her 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.
Ritzer had a Twitter account where she gave homework assignments, encouraged students and described herself as a "math teacher often too excited about the topics I'm teaching." She was a 2011 magna cum laude graduate of Assumption College in Worcester, a school spokeswoman said.
Kelleher said students related to the young teacher, who liked to wear jeans and UGG boots just like the teenagers she taught.
One of her former students, Chris Weimert, 17, said she was a warm, welcoming person who would stand outside her classroom and say hello to students she didn't teach.
"She was the nicest teacher anyone could ever have. She always had a warm smile on her face," he said.
Mary Duffy has lived next door to the Ritzers in the suburban neighborhood in Andover since the family moved there more than two decades ago. She said Colleen Ritzer had just one life ambition: to be a high school math teacher.
"All I ever heard is that she loved her job," Duffy said.
Public schools in Danvers were closed Wednesday. All schools but the high school were holding classes Thursday, while the high school was scheduled to reopen for two hours so students could meet with counselors and grief specialists. All classes were scheduled to resume Friday.
Ritzer is the second teacher allegedly killed by a student in the U.S. this week. A Sparks, Nev., middle school teacher was allegedly shot by a 12-year-old student on Monday.
Associated Press writer Lynne Tuohy in Andover and news researcher Rhonda Shafner in New York City contributed to this report.