While white-steepled churches and President Barack Obama prepared to comfort a grieving town Sunday, federal agents planned to fan out to dozens of gun stores and shooting ranges across Connecticut, chasing leads they hoped would cast light on the life of school shooter Adam Lanza.
Among the questions to be answered: Why did his mother, a well-to-do suburban divorcee, keep a cache of high-power weapons in the house? What experience did Lanza have with those guns? And, above all, what set him on a path to shoot and kill 20 children, along with the adults who tried to stop him?
Lanza shot his mother, Nancy Lanza, to death at the home they shared Friday, then drove to Sandy Hook Elementary School in her car with at least three of her guns, forced his way in by breaking a window and opened fire, authorities said. Within minutes, he killed the children, six adults and himself.
All the victims at the school were shot with a rifle, at least some of them up close, and all were apparently shot more than once, Chief Medical Examiner Dr. H. Wayne Carver said. All six adults killed at the school were women. Of the 20 children, eight were boys and 12 were girls.
Asked whether the children suffered, Carver said, "If so, not for very long." Asked how many bullets were fired, Carver said, "I'm lucky if I can tell you how many I found."
Parents identified the children through photos to spare them some shock, Carver said.
The terrible details about the last moments of young innocents emerged as authorities released their names and ages - the youngest 6 and 7, the oldest 56. They included Ana Marquez-Greene, a little girl who had just moved to Newtown from Canada; Victoria Soto, a 27-year-old teacher who apparently died while trying to hide her pupils; and principal Dawn Hochsprung, who authorities said lunged at the gunman in an attempt to overtake him.
The tragedy has 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.
Residents and faith leaders were sure to reflect Sunday on the mass shooting and what meaning, if any, to find in it. Obama planned to attend an interfaith vigil - the fourth time he will have traveled to a city after a mass shooting.
On Saturday, overflow crowds packed St. Rose of Lima Roman Catholic Church. The Rev. Richard Scinto, a deacon, gave a homily.
"In the past 48 hours I've said the phrase `I don't know' about 1,000 times," he said. "That not knowing has got to be the worst part of this whole thing."
At St. John's Episcopal Church, 54-year-old Donna Denner, an art teacher at an elementary school in nearby Danbury whose classroom was locked down after the shooting, said she feels the same way she did after 9/11 but isn't sure the rest of the country is.
"I don't know if the rest of the country is struggling to understand it the same way we are here," she said. "Life goes on, but you're not the same. Is the rest of the country - are they going about their regular activities? Is it just another news story to them?"
The rifle used was a Bushmaster .223-caliber, according to an official with knowledge of the investigation who was not authorized to speak about it and talked on condition of anonymity. The gun is commonly seen at shooting competitions and was used in a series of sniper killings in the Washington, D.C., area in 2002. Also found in the school were two handguns, a Glock 10 mm and a Sig Sauer 9 mm.
A law enforcement official said Saturday that authorities were investigating fresh leads that could reveal more about the lead-up to the shooting. The official spoke on condition of anonymity because he was not authorized to discuss the matter publicly.
ATF spokeswoman Ginger Colbrun said earlier that there was no evidence Lanza was involved in gun clubs or had trained for the shooting. When reached later in the day and asked whether that was still true, she said, "We're following any and all leads related to this individual and firearms."
Dean Price, director of the Wooster Mountain State Range - a shooting range in Danbury - said two ATF agents visited the range Friday night and stayed into the early morning looking through thousands of names on sign-in logs.
He said that he had never seen Adam or Nancy Lanza there and that agents told him they did not find their names on the sign-in sheets.
Law enforcement officials have said they've found no note or manifesto from Lanza of the sort they have come to expect after murderous rampages such as the Virginia Tech bloodbath in 2007 that left 33 people dead.
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 Friday.
Authorities said Adam Lanza had no criminal history, and 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.
Richard Novia, the school district's head of security until 2008, who also served as adviser for the school technology club, of which Lanza was a member, said he clearly "had some disabilities."
"If that boy would've burned himself, he would not have known it or felt it physically," Novia said in a phone interview. "It was my job to pay close attention to that."
Amid the confusion and sorrow, stories of heroism emerged, including an account of Hochsprung, 47, and the school psychologist, Mary Sherlach, 56, rushing toward Lanza in an attempt to stop him. Both died.
There was also 27-year-old teacher Victoria Soto, whose name has been invoked as a portrait of selflessness. Investigators told relatives she was killed while shielding her first-graders from danger. She reportedly hid some students in a bathroom or closet, ensuring they were safe, a cousin, Jim Wiltsie, told ABC News.
"She put those children first. That's all she ever talked about," a friend, Andrea Crowell, told The Associated Press. "She wanted to do her best for them, to teach them something new every day."
There was also 6-year-old Emilie Parker, whose grieving father, Robbie, talked to reporters not long after police released the names of the victims but expressed no animosity, offering sympathy for Lanza's family.
"I can't imagine how hard this experience must be for you," he said.
This article was originally published on December 15, 2012.
This program aired on December 15, 2012. The audio for this program is not available.