By Tom Winter and Lisa Riordan Seville, NBC News
Newtown shooter Adam Lanza had no clear motive, but was obsessed with Columbine and planned the rampage that took the lives of 20 children and six school staffers at Sandy Hook Elementary, "including the taking of his own life," according to a long-awaited report on last December's shooting released Monday.
"Many people have asked why the shooter did what he did on December 14, 2012," said the 48-page report, which was published on the state's Division of Criminal Justice website. "Or in the vernacular of the criminal justice system, 'Did he have a motive to do what he did?' This investigation, with the substantial information available, does not establish a conclusive motive."
The report also says that there was "no clear indication" why Lanza chose Sandy Hook for the shooting, other than that it was close to his home. The report says it is "unknown" what contribution his mental health issues made to his attack, though they interfered with his ability "to live a normal life," and that Lanza had a strained relationship with his mother Nancy, telling a witness he would not feel bad if something happened to her. Lanza shot and killed Nancy before he drove to the school.
Lanza is described as obsessed with mass shootings. "He had a familiarity with and access to firearms and ammunition and an obsession with mass murders," said the report, "in particular the April 1999 shootings at Columbine High School in Colorado. Investigators however, have not discovered any evidence that the shooter voiced or gave any indication to others that he intended to commit such a crime himself."
Investigators said Lanza had posted on an "internet blog" that "focused on mass shootings and in particular the Columbine shootings."
Police, according to the report, arrived at the school "within minutes of the first shots being fired. They went into the school to save those inside with the knowledge that someone might be waiting to take their lives."
Read the report here.
According to the report, Lanza refused to take suggested medication and didn't engage in recommended behavior therapy. Investigators found no medication in his system "that would affect his behavior."
Lanza's mother Nancy "took care of all the shooter's needs," said the report. "The mother indicated that she did not work because of her son’s condition. She worried about what would happen to the shooter if anything happened to her.”
His mother consistently described him as having Asperger's Syndrome, and said he was unable to make eye contact, was sensitive to light and didn't like to be touched. She said there were marked changes in his behavior around the seventh grade, when he became more withdrawn.
According to the report, however, a witness said Lanza "did not have an emotional connection with his mother," and said he would not feel bad if anything happened to her. "A person who knew the shooter in 2011 and 2012 said the shooter described his relationship with his mother as strained," said the report, "because the shooter said her behavior was not rational."
In November 2012, just a month before the shooting, Nancy was concerned about Adam because "he hadn't gone anywhere in three months," said the report, "and would only communicate with her by email, though they were living in the same house." Nancy Lanza, however, never expressed fear for herself or anyone else at the hands of her son.
The long-awaited summary of the second-deadliest mass shooting in U.S. history omitted much information from the investigative file, including transcripts of 911 calls, some witness statements from children and all crime scene photos.
The release of the report, initially expected over the summer, was pushed back several times amid growing pressure from from authorities -- including Connecticut Gov. Dannel P. Malloy -- to release more information.
Throughout the investigation, State’s Attorney Stephen Sedensky III has resisted efforts by the news media and some public officials to release more information related to the shooting.
In March, he ordered police to stop discussing details of the investigation at conferences after the New York Daily News reported that state police Col. Danny Stebbins told audience members at a law enforcement conference in New Orleans that Lanza had created a spreadsheet of mass killings going back 30 years.
He and the town of Newtown also went to court to try and prevent the release of 911 calls from the school or transcripts of them, arguing that making them public could jeopardize the investigation. The state's Freedom of Information Commission ruled in September that the recordings should be provided to the news media, but a prosecutor obtained a stay while he appeals that order. At a hearing in New Britain, Conn. on Monday morning, a judge said he would listen to the recordings and issue a ruling on whether they can be made public.
The summary also represents only a small portion of the investigation by both state and federal authorities. It does not include the entire state police evidence file, which runs thousands of pages, according to Paul Vance, spokesman for the Connecticut State Police.
The full report is expected to be released once Sedensky declares the investigation closed, though no date has been announced.
And some evidence from the state's investigation may never be made available to the public.
A Connecticut law passed earlier this year in response to the shooting prohibits the release of photographs, film, video and other visual images showing a homicide victim if they can "reasonably be expected to constitute an unwarranted invasion of personal privacy of the victim or the victim's surviving family members."
Before its release, Sedensky’s office and local authorities did everything they could to brace townspeople for the coming onslaught of attention.
Sedensky allowed victims' relatives to review the report at briefings over the previous two weeks.
And the interim superintendent of schools in Newtown advised parents to think about limiting their children's exposure to media reports on Monday and to reach out to mental health professionals if family members need help coping with the contents of the report or the approaching anniversary.
"We all understand that for the children who were directly affected by this tragedy the release of the report and the upcoming anniversary can carry a very personal meaning," read the Nov. 19 letter from Dr. John Reed.
NBCConnecticut, the Associated Press and Reuters contributed to this report.