Danvers High School teacher Colleen Ritzer is seen in this undated picture provided by Ritzer's family.
/ AP Photo/Courtesy of Dale Webster via the Lawrence Eagle-Tribune
Danvers, Massachusetts (CNN) -- The details are unsettling: a teacher killed, sources say, with a box cutter in a bathroom of the school where she loved to teach; her 14-year-old student picked up and accused in the death hours later, allegedly after cleaning up, he hit a fast food restaurant and took in a movie.
Earlier: Teen charged in murder of teacher Colleen Ritzer
But there was no answer to perhaps the most unsettling question of all -- why? -- on Thursday, two days after police say Danvers High School math teacher Colleen Ritzer died at the hands of student Philip Chism.
Chism has been in custody since the first hour of Wednesday, when police saw him walking under the pitch-dark sky on a busy road. What he'd allegedly done before then became clearer Thursday, including authorities' contention that he'd killed Ritzer with a box cutter he'd brought to school and wheeled her body outside in a recycling bin, a source close to the investigation told CNN's Pamela Brown.
See also: Student held without bail in teacher's death
The killer dropped the woman's body about 20 feet into the woods behind the northeastern Massachusetts high school's athletic fields, and didn't bury or cover it, according to another source familiar with the investigation.
Investigators also found a recycling bin that appeared to have been thrown off an embankment some 100 feet away, the source said.
After the killing, Chism changed his clothes, according to two law enforcement sources, and then went to a Wendy's restaurant, according to the source who spoke Thursday to CNN about the crime scene. Another source said Wednesday that he also had gone to the movies.
Chism remained jailed without bond on Thursday, accused of murder as an adult in Ritzer's brutal death.
He was a student in one of Ritzer's classes, the Essex County District Attorney's Office explained. Authorities haven't said what may have provoked the boy -- described by friends, family and co-workers as reserved and well-behaved -- to kill.
While investigators worked to figure that out, there were no classes Thursday in the school that had linked the two, an opportunity for students to grieve with friends and seek advice from counselors.
"It's just surreal how quickly someone can go, and how much we take for granted every day," said Danvers High School student Chris Weimert. "(Ritzer was) he nicest teacher you could ever have," he said. "I can't believe it."
A missing-person case
The ordeal started Tuesday as a missing-person case. Authorities first searched for Chism after he was reported missing. They alerted the public Tuesday evening that the teen had been last seen around 6:30 p.m. But around 11:20 p.m., they got a call that 24-year-old Ritzer had also disappeared.
She hadn't returned home and was not answering her phone, said District Attorney Jonathan Blodgett. Police in Topsfield, the town just north of Danvers, spotted Chism walking there around 12:30 a.m.
At the high school, police found blood in a second-floor bathroom, the district attorney said. The teacher's body was soon discovered behind the school.
Detectives interviewed Chism, and whatever the teen told them about what went on at the school and in the surrounding woods, coupled with video surveillance, led to an arrest.
Authorities arraigned Chism on Wednesday in Salem. A judge ordered him held without bond pending a November 22 probable cause hearing.
The Essex County District Attorney's Office issued a statement saying it will ask a grand jury to indict Chism for murder. According to Massachusetts law, juveniles ages 14 or older are treated as adults by the court if they're charged with first- or second-degree murder.
A quiet and normal student
Chism is a quiet young man, those who know him said. He excelled at soccer and made a harmless impression.
"He ... seemed quiet and reserved, but he just seemed normal," said Ariana Edwards, who was in Chism's English class.
Chism didn't drink or do drugs, and he came from a good family, one of his closest friends said. He described Chism as a good athlete who was shy at first but eventually warmed up to people, adding that he hadn't been acting strangely lately.
This friend and others got their first hint that something was awry when Chism didn't show up for soccer practice Tuesday. The team set out to look for him after seeing texts that he was missing.
He was a newcomer to Danvers, a town of about 26,000 people. His family had bounced around, and he had lived in different cities in Tennessee and Florida since he was in fourth grade, authorities in those states said.
A teacher who went the extra mile
Meanwhile, many were at a loss in Danvers to make sense of Ritzer's death. She posted inspirational messages on her Twitter account and went the extra mile to help students.
"She was talking on Saturday about this year was a good year. She was teaching freshmen for first time. She was happy," said Jen Berger, Ritzer's best friend. "I don't even know what the world is like without her. It's a scary thought."
Sympathy spread through the region, making its way into the baseball World Series. Bleachers full of fans who had assembled to watch the Boston Red Sox take on the St. Louis Cardinals observed a moment of silence in Ritzer's honor before Game 1 began Wednesday night at Boston's Fenway Park.
Ritzer, a 2011 graduate of Assumption College who was working towards a master's degree at Salem State University, seemed to always wear a wide smile and was approachable to students and colleagues alike, said Charlotte Dzerkacz, who became good friends with Ritzer in 2011 when they taught at the same middle school.
"She was energetic, she was compassionate," Dzerkacz said. "You couldn't ask for anything more from a teacher or a friend."
Salem State issued a statement lamenting Ritzer's death.
"She believed children have much to offer and often do not realize how special they are as individuals," the university said. "In her application to Salem State she said she was dedicated to 'helping students in times of need.'"
Ritzer was known to take to Twitter to dole out homework assignments and wisdom to her students.
"No matter what happens in life, be good to people," she wrote in August. "Being good to people is a wonderful legacy to leave behind."