Monday afternoon, the Connecticut State Attorney's office released the full report from the investigation into last December's shooting at Sandy Hook Elementary School in Newtown. Terrifying as it is detailed, the report covers Adam Lanza's path through the school, his possessions, and his possible motives.

The document lists an extensive timeline from the shooting. The morning of December 14, 2012, Lanza shot his way into the school using a Bushmaster Model XM15-E2S rifle and killed the school's principal and school psychologist in the hallway near the front office. He then walked into two classrooms and shot four teachers and 20 children to death before committing suicide. From the report:

The response to these crimes began unfolding at 9:35:39 a.m. when the first 911 call was received by the Newtown Police Department. With the receipt of that call, the dispatching and the arrival of the police, the law enforcement response to the shootings began. It was fewer than four minutes from the time the first 911 call was received until the first police officer arrived at the school. It was fewer than five minutes from the first 911 call, and one minute after the arrival of the first officer, that the shooter killed himself. It was fewer than six minutes from the time the first police officer arrived on SHES property to the time the first police officer entered the school building. In fewer than 11 minutes twenty first-grade pupils and six adults had lost their lives.

Also included in the report is an extensive itemization of Lanza's possessions. In addition to many video games, police found news articles about prior mass shootings at schools in Lanza's room. Some of the items discovered, from the report:

- A Christmas check from the mother to the shooter to purchase a CZ 83 firearm;39

- A New York Times article from February 18, 2008, regarding the school shooting at Northern Illinois University;

- Three photographs of what appear to be a dead human, covered in blood and wrapped in plastic;

- The book Amish Grace: How Forgiveness Transcended Tragedy, Jossey-Bass, 2007, by Donald B. Kraybill, Steven Nolt and David Weaver-Zercher;

- Photocopied newspaper articles from 1891 pertaining to the shooting of school children

And here are the digital files that authorities believe belonged to Lanza, which included several spreadsheets about mass murders:

- Bookmarks pertaining to firearms, military, politics, mass murder, video games, music, books, Army Ranger, computers and programs, ammunition, candy, economic books

- Web page design folders

- Two videos showing suicide by gunshot

- Commercial movies depicting mass shootings

- The computer game titled "School Shooting" where the player controls a character who enters a school and shoots at students

- Screen shots (172) of the online game "Combat Arms"

- "Dance Dance Revolution" (DDR) game screen shots

- Videos of shooter playing DDR

- Images of the shooter holding a handgun to his head

- Images of the shooter holding a rifle to his head

- Five-second video (dramatization) depicting children being shot

- Images of shooter with a rifle, shotgun and numerous magazines in his pockets

- Documents on weapons and magazine capacity

- A document written showing the prerequisites for a mass murder spreadsheet

- A spreadsheet listing mass murders by name and information about the incident

- Materials regarding the topic of pedophilia and advocating for rights for pedophiles (not child pornography)

- Large amount of materials relating to Columbine shootings and documents on mass murders

- Large amount of materials on firearms

- Comedy videos

- Music

- Images of hamsters

- Images of Lego creations

Even with the above evidence, investigators still don't have a definitive motive for the shooting. From the report's summary:

The obvious question that remains is: "Why did the shooter murder twenty-seven people, including twenty children?" Unfortunately, that question may never be answered conclusively, despite the collection of extensive background information on the shooter through a multitude of interviews and other sources. The evidence clearly shows that the shooter planned his actions, including the taking of his own life, but there is no clear indication why he did so, or why he targeted Sandy Hook Elementary School.

It is known that the shooter had significant mental health issues that affected his ability to live a normal life and to interact with others, even those to whom he should have been close. As an adult he did not recognize or help himself deal with those issues. What contribution this made to the shootings, if any, is unknown as those mental health professionals who saw him did not see anything that would have predicted his future behavior. He had a familiarity with and access to firearms and ammunition and an obsession with mass murders, 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.

Read the full report here.

[Image via AP]