HARTFORD, Conn. - A report on the Newtown school shooting says that the gunman had an obsession with mass murders but that investigators did not discover any evidence he had indicated to others an intention to carry out such a crime.
The summary of the investigation by Connecticut State's Attorney Stephen Sedensky says Adam Lanza was obsessed in particular with the April 1999 shootings at Columbine High School in Colorado.
The report on the Dec. 14 massacre of 20 children and six adults says the question of Lanza's motive may never be answered conclusively.
Lanza killed his mother inside their Newtown home before driving to Sandy Hook Elementary School and carrying out his rampage.
A timeline released with the report Monday says the first officer arrived behind the school at 9:39 a.m. after the shooting was reported. Two other Newtown officers then arrived at the school, and gunshots were heard in the background.
The last gunshot officers heard, which is believed to be the suicide shot by gunman Adam Lanza, was heard at three seconds past 9:40.
Sedensky wrote in the report that law enforcement officers were operating under the belief there may have been more than one shooter.