Inside the rambling, pale-yellow Colonial-style home in a Connecticut suburb, Adam Lanza lived amid a stockpile of disparate weaponry and macabre keepsakes: a pair of rifles, 11 knives, a starter pistol, a bayonet, three samurai swords. He saved photographs of what appeared to be a corpse smeared in blood and covered in plastic. Nearby was a newspaper clipping that chronicled a vicious shooting at Northern Illinois University in 2008.
In what investigators believed was his bedroom was a gun safe. Among his clothing was a military-style uniform. There was also a holiday card that contained a check made out to Lanza, 20, and signed by his mother. Investigators suggested that the money had been intended to buy a gun.
The disturbing details of Lanza's possessions were disclosed Thursday for the first time since he carried out the massacre at Sandy Hook Elementary School in Newtown, Conn., one of the deadliest school shootings in the nation's history. The information was included in search warrants and related affidavits connected to the investigation into the Dec. 14 attack, when he killed 20 first-graders, six educators, his mother and himself.
The inventory of the house, combined with interviews conducted over several weeks with law-enforcement officials and people who crossed paths with the Lanza family, afford a somewhat fuller picture of the dark corners of Lanza's mind.
The interviews revealed that his mother, Nancy Lanza, confided to friends several years ago that her son, who classmates said had been found to have a type of autism, was faring poorly and being bullied in high school. More recently, he had cocooned himself in front of electronic game consoles in the basement of their home, playing war games.
The contents of the Lanza house of are intense interest because the lives of the family have been picked apart since the shootings, often yielding little insight. A clear understanding of Adam Lanza's thinking and the texture of his relationship with his mother and others has yet to emerge. What pushed him to his brutality may never be unraveled.
After killing his mother at their home on the morning of Dec. 14, Lanza drove to the grade school that he once attended and carried out the massacre in less than five minutes, according to the search warrant.
The rampage brought the nation and the world to tears and touched off a continuing national debate over gun control.
Stephen Sedensky III, the state's attorney who is in charge of the investigation, said in a statement Thursday that Lanza shot his mother in the forehead with a .22-caliber rifle while she was in bed in her second-story bedroom.
At the school, he used a Bushmaster XM15-E2S semiautomatic rifle to fire 154 shots, the statement said. The police also found 10 30-round magazines for the gun, many of them partly or fully emptied.
Lanza also carried two semiautomatic handguns, one of which he used to kill himself. The police found a 12-gauge shotgun in the car he drove to the school.
The inventories attached to the warrants delineated pertinent items found by police in the home that Lanza shared with his mother, a two-story house with dark green shutters. Nancy Lanza was a gun enthusiast who often took her son to shooting ranges. She was divorced from his father, Peter Lanza, a General Electric executive.
The items included hundreds of rounds of ammunition, some of them housed in a Planters peanut can and a Nike shoe box, and a panoply of weapons found in a brown safe and in bedroom closets. The lists mention four guns, including the one found in the black Honda Civic that Lanza drove to Sandy Hook. There were two rifles, including the one used to kill Nancy Lanza, as well as a BB gun and a starter pistol.
The police also found a certificate from the National Rifle Association bearing the name Adam Lanza. The type of certificate was not clear. The organization said Thursday that Adam Lanza and Nancy Lanza were not members.
There was also a receipt from a shooting range in Oklahoma, an NRA guide to the basics of pistol shooting and training manuals on the use of a variety of firearms.
There were paper and cardboard gun targets, as well as a considerable amount of computer equipment and game consoles and equipment. There was a hard drive that appeared to have been deliberately smashed.
There were numerous books connected to autism. One was titled, "Born on a Blue Day -- Inside the Mind of an Autistic Savant."
Classmates of Lanza and others who knew the family have said he had an autism variant known as Asperger syndrome, though investigators have never confirmed that diagnosis. Even so, his association with the disorder has raised alarms among parents of children with the diagnosis, who have expressed concerns that the public might believe that those with autism are prone to violence.
Though Lanza's life remains mostly opaque, interviews in recent weeks show that he was a socially fragile individual captivated by warfare video games and bent on military service.
Marvin LaFontaine, 53, a mechanical engineer who considered himself a friend of Nancy Lanza from Kingston, N.H., where Lanza grew up, kept in touch with her chiefly by email, Facebook and phone until 2010. He remembered that Adam Lanza deeply admired one of his mother's brothers, a retired Kingston police officer named James Champion.
Mr. LaFontaine said Lanza was keen on joining the military, as his uncle, Champion, had done.
Classmates said Lanza was smart but acutely shy, and was not known to have close friends. His mother frequently moved him in and out of school, and at times home-schooled him. Several years ago, when Lanza was in high school, Mr. LaFontaine said Lanza shared with him that "the problems with Adam were getting worse and that he was getting picked on and bullied and was starting to shut down."
A Newtown rabbi who counseled the families of victims of the shooting said former classmates of Lanza had told him that Lanza was sometimes the object of ridicule in high school. Other classmates have said they did not recall instances of him being bullied.
Mr. LaFontaine said Nancy Lanza had been weighing a number of options, which included again removing him from school, which she later did. Adam Lanza left Newtown High School after 10th grade. For a time, he attended college.
Despite his issues, Mr. LaFontaine recalled, "Nancy was generally confident that he could beat this and grow up into a normal, confident man, and that she could help him to do that."
Adam Lanza had cut off contact with his father and his older brother, Ryan, in recent years, according to various accounts.