Investigators on Saturday worked to understand what led a bright but painfully awkward 20-year-old to slaughter 26 children and adults at a Connecticut elementary school, while townspeople took down Christmas decorations and struggled with how to get through a holiday season that has suddenly become a time of mourning.
The tragedy spurred soul-searching and grief around the globe. Families as far away as Puerto Rico began to plan funerals for victims who still had their baby teeth, world leaders extended condolences, and vigils were held around the U.S.
Amid the sorrow, stories of heroism emerged, including an account of the Sandy Hook Elementary School principal who lost her life lunging at the gunman, Adam Lanza, in an attempt to overpower him.
Police shed no light on the motive for the second-deadliest school shooting in U.S. history, though state police Lt. Paul Vance said investigators had found "very good evidence ... that our investigators will be able to use in painting the complete picture, the how and, more importantly, the why." He would not elaborate.
However, another law enforcement official, speaking on condition of anonymity, said investigators have found no note or manifesto of the sort they have come to expect after murderous rampages such as the Virginia Tech bloodbath in 2007 that left 33 people dead.
The mystery deepened as Newtown education officials said they had found no link between Lanza's mother and the school, contrary to news reports that said she was a teacher there. Investigators said they believe Adam Lanza attended Sandy Hook Elementary many years ago, but they had no explanation for why he went there on Friday.
Lanza shot and killed his mother, Nancy Lanza, at the home they shared, then drove to the school in her car with at least three of her guns, forced his way inside and opened fire in two classrooms, authorities said. Within minutes, he killed 20 children, six adults and himself.
On Saturday, Chief Medical Examiner Dr. H. Wayne Carver said all the victims at the school were killed up close and shot more than once.
The tragedy plunged Newtown into mourning and added the picturesque New England community of handsome colonial homes, red-brick sidewalks and 27,000 people to the grim map of towns where mass shootings in recent years have periodically reignited the national debate over gun control but led to little change.
Signs in downtown Newtown read, "Hug a teacher today," "Please pray for Newtown" and "Love will get us through."
"People in my neighborhood are feeling guilty about it being Christmas. They are taking down decorations," said Jeannie Pasacreta, a psychologist who was advising parents struggling with how to talk to their children.
Authorities had yet to release the list of the dead, but in the tightly knit town, nearly everyone seemed to know someone who died.
Among the dead: well-liked Principal Dawn Hochsprung, who town officials say tried to stop the rampage and paid with her life; the school psychologist who probably would have helped survivors grapple with the tragedy; a teacher thrilled to have been hired this year; and a 6-year-old girl who had just moved to Newtown from Canada.
Authorities said Lanza had no criminal history; it was not clear whether he had a job. Lanza was believed to have suffered from a personality disorder, said a law enforcement official who spoke on condition of anonymity.
Another official, also speaking on condition of anonymity, said Lanza had been diagnosed with Asperger's, a mild form of autism that is often characterized by social awkwardness. People with the disorder are often highly intelligent. While they can become frustrated more easily, there is no evidence of a link between Asperger's and violent behavior, experts say.
The officials insisted on anonymity because they were not authorized to discuss the unfolding investigation.
Acquaintances describe the former honor student as smart but odd and remote.
"He was very different and very shy and didn't make an effort to interact with anybody" in his 10th-grade English class, said Olivia DeVivo, now a student at the University of Connecticut. Lanza always came to school toting a briefcase and wearing his shirt buttoned all the way up, she said.
"You had yourself a very scared young boy, who was very nervous around people," said Richard Novia, who was the district's head of security and adviser to the school's Tech Club, of which Lanza was a member. He added: "He was a loner."
Novia said Lanza had extreme difficulties relating to fellow students and teachers, as well as a strange bodily condition: "If that boy would've burned himself, he would not have known it or felt it physically."
Lanza would also go through crises that would require his mother to come to school to deal with. Such episodes might involve "total withdrawal from whatever he was supposed to be doing, be it a class, be it sitting and read a book," Novia said.
When people approached Lanza in the hallways, he would press himself against the wall or walk in a different direction, clutching his black case "like an 8-year-old who refuses to give up his teddy bear," said Novia, who now lives in Tennessee.
Even so, Novia said his primary concern about Lanza was that he might become a target for teasing or abuse by his fellow students, not that he might become a threat.
"Somewhere along in the last four years there were significant changes that led to what has happened Friday morning," Novia said. "I could never have foreseen him doing that."
Sandy Hook Elementary will be closed next week - some parents can't even conceive of sending their children back, Board of Education chairwoman Debbie Leidlein said - and officials are considering what to do about the town's other schools.
"Next week is going to be horrible," said the town's legislative council chairman, Jeff Capeci, thinking about the string of funerals the town will face. "Horrible, and the week leading into Christmas."
Asked whether the town would recover, Maryann Jacob, a clerk in the school library who took cover in a storage room with 18 fourth-graders during the shooting rampage, said: "We have to. We have a lot of children left."