A police report into the Sandy Hook school massacre has revealed harrowing new details about the murders and the gunman's family life.
The paperwork, much of which is blacked out, includes several videos and hundreds of photographs from inside Sandy Hook Elementary and Adam Lanza's home.
It reveals how police officers were faced with terrible scenes inside the school and describes how many of the children were killed in a bathroom where they were hiding.
Lanza shot and killed his mother at their home before driving to the Newtown school, where he killed 20 children and six teachers.
A rifle magazine clip is seen on the floor in the hallway
The 20-year-old then committed suicide by shooting himself in the mouth with a handgun as police arrived at the scene.
Included in the files were photographs showing bullet holes in walls, windows and classroom furniture.
Images of spent magazine clips and empty shell casings on the floor depict the gunman's path of destruction.
The report also included many photographs of the contents of the gunman's family house - including one of a young child holding what appears to be a gun, with ammunition in his lap.
In a letter accompanying the report, Reuben Bradford, commissioner of the state Department of Emergency Services and Public Protection, praised the efforts of all those connected to the horrific shooting.
He wrote: "In the midst of the darkness of that day, we also saw remarkable heroism and glimpses of grace. We saw Sandy Hook Elementary School faculty and staff doing everything in their power to protect their charges.
A gun seen just inside one of the classrooms
"The investigation of this incident is unparalleled in the 110-year history of the Connecticut State Police."
The documents revealed that a former teacher of Lanza's was quoted as telling investigators that Lanza exhibited anti-social behaviour, rarely interacted with other students and obsessed in writings "about battles, destruction and war".
"In all my years of experience, I have known (redacted) grade boys to talk about things like this, but Adam's level of violence was disturbing," the teacher told investigators.
The teacher added: "Adam's creative writing was so graphic that it could not be shared."
The documents also filled in more details about how the shooting unfolded, teachers protected their students and the school janitor confronted the shooter.
Teachers heard janitor Rick Thorn try to get Lanza to leave the school.
One teacher, who was hiding in a closet in the maths lab, heard Mr Thorn yell: "Put the gun down!"
An aide said she heard gunfire and Mr Thorn told her to close her door.
The documents' release marks the end of the investigation into the massacre on December 14, 2012,
Prosecutors issued a summary of the investigation last month that portrayed Lanza as obsessed with mass murders.
Lanza kept a clipping about the 2008 Northern Illinois University shooting
But the report concluded that Lanza's motives for the massacre might never be known.
Lanza "was undoubtedly afflicted with mental health problems; yet despite a fascination with mass shootings and firearms, he displayed no aggressive or threatening tendencies," it said.
Lanza was diagnosed in 2006 with "profound autism spectrum disorder, with rigidity, isolation and a lack of comprehension of ordinary social interaction and communications".
He also displaying symptoms of obsessive-compulsive disorder.
Kathleen Koenig, a nurse at the Yale Child Studies Center, told investigators that Lanza frequently washed his hands and changed his socks 20 times a day, to the point where his mother did three loads of laundry a day.
The nurse, who met with Lanza in 2006 and 2007, said Lanza's mother declined to give him prescribed antidepressant and anti-anxiety medication after she reported that he had trouble raising his arm, something she attributed to the drug.
Koenig unsuccessfully tried to convince Nancy Lanza that the medicine was not responsible, and the mother failed to schedule a follow-up visit after her son missed an appointment, police said.
In the documents, a friend told police that Nancy Lanza reported that her son had hit his head several days before the shootings.
And an ex-boyfriend told police that she cancelled a trip to London on the week of the shooting because of "a couple last-minute problems on the home front".
She told a friend two weeks before the shootings that her son was growing "increasingly despondent" and had refused to leave his room for three months.
They only communicated by email, with the mother saying he told her he wouldn't feel bad if something happened to her.
His isolation was so complete that he refused to leave his room during Superstorm Sandy, the report said.
Just before the shooting, Nancy Lanza was in New Hampshire. She told a lunch acquaintance there that the trip was an experiment in leaving her son home alone in Connecticut for a few days.
Photographs from inside the Lanza home show numerous rounds of ammunition, gun magazines, shot-up paper targets, large knives and swords.
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