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 with a rifle and were shot more than once. All six adults killed at the school were women. Of the 20 children, eight were boys and 12 were girls. All the children were 6 or 7 years old.
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 around town 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.
In the tightly knit town, nearly everyone seemed to know someone who died. Among them: 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 law enforcement official, also speaking on condition of anonymity, said Lanza had been diagnosed with Asperger's, a mild form of autism 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 law enforcement 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.
Olivia DeVivo, now a student at the University of Connecticut, recalled that Lanza always came to school toting a briefcase and wearing his shirt buttoned all the way up. "He was very different and very shy and didn't make an effort to interact with anybody" in his 10th-grade English class, she said.
"You had yourself a very scared young boy who was very nervous around people," said Richard Novia, who was 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 main concern about Lanza was that he might become a target for teasing or abuse by other 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 deciding 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."
Names and ages of those killed in Conn. rampage
Names and ages of the 26 people gunned down at a Connecticut elementary school Friday in the second-deadliest school shooting in U.S. history:
Charlotte Bacon, 6
Daniel Barden, 7
Rachel Davino, 29
Olivia Engel, 6
Josephine Gay, 7
Ana Marquez-Greene, 6
Dylan Hockley, 6
Dawn Hochsprung, 47
Madeleine Hsu, 6
Catherine Hubbard, 6
Chase Kowalski, 7
Jesse Lewis, 6
James Mattioli, 6
Grace McDonnell, 7
Anne Marie Murphy, 52
Emilie Parker, 6
Jack Pinto, 6
Noah Pozner, 6
Caroline Previdi, 6
Jessica Rekos, 6
Avielle Richman, 6
Lauren Rousseau, 30
Mary Sherlach, 56
Victoria Soto, 27
Benjamin Wheeler, 6
Allison Wyatt, 6
Source: Connecticut State Police