He was a loner, a 20-year-old whom Newtown High School classmates remembered as a skinny, shaggy-haired boy "who never really talked at all" and who stayed tight to the corridor walls when he walked, often clutching his laptop.
There was a common refrain among acquaintances of Adam Lanza: I knew of him but I didn't know him.
Lanza kept to himself. Over several bloody minutes Friday morning, armed with a rifle, Lanza emerged from his shell long enough to destroy the lives of 20 first-graders and six adults at Sandy Hook Elementary School. He'd gone to the school as a youth, a former classmate said.
On Friday morning, he drove to the school after killing his mother, Nancy Lanza, 52, in herhome2 miles away on Yogananda Street, law enforcement sources said. She was still in bed when he shot her, the sources said.
Adam Lanza had lived with his mother in the 4,000-square-foot, $700,000 house. His parents were divorced in 2009.
He had two bedrooms that were clean and orderly when law officers swept into the house after the shootings Friday morning. Lanza apparently lived in one of the rooms and kept his computer gear and other items in the other one, the sources said. Law officers found evidence that Adam Lanza played graphically violent video games, the sources said.
Lanza was estranged from his brother, Ryan Lanza, 24, and hadn't talked to his father since 2010, according to people who have known the family. Ryan, a graduate of Quinnipiac University in Hamden, works for the financial firm Ernst &Young and lives in an apartment in Hoboken, N.J.
Marsha Lanza, Adam Lanza's aunt, said it was her understanding that Nancy Lanza kept three guns in the home.
"Nancy was meticulous," Marsha Lanza told reporters outside her home in Crystal Lake, northwest of Chicago. "She would never leave the guns out."
Marsha Lanza called Nancy Lanza "self-reliant."
"The only reason she would have guns," Marsha Lanza said, "was for self-defense."
Two law enforcement sources said the murder weapon was one of those guns, a semiautomatic rifle. The others were a pair of semiautomatic pistols.
But why Adam Lanza embarked on the deadliest rampage at an elementary school in U.S. history is an open question. Law officers have a sense of his home life, but they have yet to nail down a motive.
The sources said investigators believe Adam Lanza's isolation and social awkwardness were consistent with Asperger's syndrome. Asperger's is a disorder that is part of the autism spectrum. It is marked by difficulty with social interaction. Many with Asperger's are otherwise high-functioning people. There is no pre-disposition toward violence, experts said.
"It's very important for people to know that there is absolutely no correlation between the diagnosis of Asperger's syndrome and a predilection toward violent behavior,'' said Dr. Harold Schwartz, chief psychiatrist at the Institute of Living in Hartford.
The reasons someone may suddenly commit unfathomable violence are, at best, elusive.
"Frankly, it is the kind of question no one can answer, but there are patterns,'' said Schwartz. "There are 'grievance collectors,' people who walk around feeling deeply aggrieved and harboring enormous resentments. But they don't have the skill to address what they are feeling in any productive way.
"They can act out, and through some fantastic thinking, believe that somehow the world will understand the depth of their pain when others see what they have done,'' said Schwartz.
Adam Lanza's relatives were at a loss to explain his actions.
"Like you, we want to know why," said Marsha Lanza. "My heart goes out to all the families."
'Painfully Shy,' 'Strange'
Andrew Lapple sat next to Lanza in homeroom in their senior year at Newtown High.
Lapple described him as a skinny, reserved kid "who never really talked at all."
Lanza tried his hand at Little League baseball but wasn't very good. He was more of a "tech-geek," Lapple said.
"He was always carrying around his laptop holding onto it real tight,'' Lapple said. "He walked down the halls against the wall almost like he was afraid of people. He was definitely kind of strange but you'd never think he'd do something like this."
Rebecca Jaroszewski said she was in the same first- and third-grade classes with Lanza at Sandy Hook Elementary. She said the memory that stands out most is Lanza standing alone while other children played at recess, straining himself to make his face turn red and making animal-like noises.
He did this often, Jaroszewski said. "He would seem really angry, but he wouldn't tell people why," she said.
When she heard the news about the shootings, "It clicked for me when I realized who it was," Jaroszewski said.
Another former classmate of Lanza's remembered him as quiet and shy and socially awkward.
Kateleen Foy, now an undergraduate at Hofstra University in New York, said she was in Lanza's seventh-grade class at St. Rose of Lima School in Newtown.
She recalled that he joined the class after the school year began and left before school got out for the summer.
"He was really shy, really painfully shy," Foy said. "He was a little hard to talk to."
Foy said she didn't recall seeing Lanza again after he left St. Rose until she spotted him in a hall while they were students at Newtown High School.
"I want people to know he wasn't always a monster," Foy said. "He became one, but he wasn't always that way."
Foy said she and other students accepted his shyness because, she said, he had been home-schooled and "hadn't really been socialized."
In high school, "There were never any concrete signs of anything like [violence]. He went with the flow. … He flew under the radar,'' Foy said.
Another high school classmate, Ryan Schmidt, said Lanza "kept to himself. … He was just a bit off. He seemed like he was always awkward and looking around expecting something or someone to be coming at him. Twitchy, almost."
Cindy Kromberg, mother of one of Lanza's Newtown High classmates, Kyle Kromberg, recalled Lanza as "such a quiet, odd child." She said he was "a kid that didn't make eye contact, very introverted, very shy, very odd, very not mainstream."
Nicholas Martinez, who rode the school bus with Lanza when they were both seventh-graders at St. Rose of Lima, recalled talking with Lanza about classic rock, which they both enjoyed. Martinez said he remembered that Lanza had been home-schooled for a time.
"Looking back now," Martinez said, "it just seems like there was a lot beneath the surface that was never attended to."
Marsha Lanza said she considered her nephew "very bright, very brilliant. I guess he was what you might call a computer geek."
Those who know Adam Lanza's parents were grieving for the mother and expressing sympathy for the father.
His father, Peter Lanza, an accountant, lives in Stamford with his second wife.
On Saturday afternoon, Stamford police stood guard outside his home, and residents from the affluent north Stamford neighborhood slowed down while driving past the line of press cars and SUVs parked along the street.
A neighbor, Tony Battinelli, said Lanza has lived in the modest, older, one-story gray house for a year or two.
"As a parent, I feel for him. I can't imagine what he's going through right now," Battinelli said.
Peter Lanza released the following statement through an intermediary:
"Our hearts go out to the families and friends who lost loved ones and to all those who were injured. Our family is grieving along with all those who have been affected by this enormous tragedy. No words can truly express how heartbroken we are.
"We are in a state of disbelief and trying to find whatever answers we can. We too are asking why. We have cooperated fully with law enforcement and will continue to do so. Like so many of you, we are saddened, but struggling to make sense of what has transpired."
Friends and neighbors on Yogananda Street in Newtown said Nancy Lanza was a kind woman with a sense of humor. Slender, with short hair, she was a fixture at neighborhood events such as the Labor Day parade, and had a flair for setting up Christmas lights.
Neighbors said the hilly, affluent neighborhood in the east end of town is a children- and family-friendly place. The description was affirmed by the children riding their bikes and the folks walking their dogs despite the crush of TV trucks and reporters waiting near the Lanza home.
Rhonda Cullens, Nancy Lanza's friend and neighbor, fought back tears Friday afternoon in the doorway of her home on Founders Lane, around the corner from the Lanza residence.
She said she met Nancy Lanza playing bunco, a popular dice game, with a group of women in the neighborhood, but she hadn't seen her for years since she stopped playing with the group. "She was just a sweet, caring person," Cullens said.
Courant staff reporters Dave Altimari, Brian Dowling, Susan Dunne, Kenneth Gosselin, Jesse Leavenworth and Don Stacom contributed to this story. Information from Chicago Tribune correspondent Mark Shuman is also included.Copyright © 2015, The Baltimore Sun