Prosecution can't explain why Adam Lanza carried out Newtown massacre
Prosecutors mystified as to why young gunman carried out school shootings
The motivations of the gunman who killed 20 schoolchildren in Newtown, Connecticut, last year is still a mystery and may never be known with certainty, prosecutors said in a report that ended their investigation.
Adam Lanza, 20, was obsessed with mass murders and the 1999 Columbine High School shooting in particular, but investigators did not find evidence he ever told others of his intentions to carry out such an attack.
Lanza killed the children and six educators with a semi-automatic rifle inside Sandy Hook Elementary on December 14. He shot and killed his mother inside their home before driving to the school, and killed himself with a handgun as police arrived.
The new report describes a gunman who had "significant mental health issues" but had knowledge of what he was planning: he had materials on mass murder, he smashed his computer hard drive, and he used earplugs during the shooting.
"The obvious question that remains is: 'Why did the shooter murder 27 people, including 20 children?' Unfortunately, that question may never be answered conclusively," the report said.
Lanza's mother, Nancy Lanza, was concerned for her son and said he hadn't gone anywhere in three months and would communicate with her by e-mail only, even though they were living in the same house. She never expressed fear that she or anyone was in danger from her son, the report said.
The lead investigator, State's Attorney Stephen Sedensky, said there was no clear indication why Lanza chose the school as the target other than it was close to his home.
The report said Lanza was diagnosed with Asperger's disorder in 2005 - but "what contribution this made to the shootings, if any, is unknown."
Documents with the report show Lanza wrote a violent book as a child that included a character who shoots his mother.