Police in Connecticut have released more information on the events surrounding Adam Lanza's massacre of 20 children, six teachers and his own mother in Sandy Hook last year.
Documents have been released after the expiration of a 90-day confidentiality order.
On December 14 2012, the 20-year-old shot his mother in the forehead.
He then drove a Honda Civic to Sandy Hook elementary school and - wearing a bulletproof vest and military fatigues - shot his way into the buildings.
Five minutes later he was dead, along with his 26 school victims.
State Attorney Stephen J Sedensky III said Lanza killed all 26 victims inside Sandy Hook Elementary School with a Bushmaster .223-caliber rifle before taking his own life with a Glock 10mm handgun. He added that Lanza had another loaded handgun with him inside the school as well as three 30-round magazines for the Bushmaster.
Police later found a 12-gauge shotgun in the Honda's glove compartment with two magazines containing 70 rounds of Winchester 12-gauge shotgun rounds, and an arsenal of weapons including guns, a gun safe with shotgun shells, a bayonet and several swords in the home Lanza shared with his mother, Nancy.
There were also three photos of "what appears to be a deceased human covered in plastic and what appears to be blood," and a New York Times article from February 2008 about a shooting at Northern Illinois University.
They also found books about autism and Asperger's syndrome as well as an NRA guide to pistol shooting.
An unnamed source told investigators that Lanza was an avid gamer who played Call of Duty and other games, rarely leaving his home. In his bedroom were found a smashed computer hard drive, and a games console.
Investigators found articles on other shootings and a holiday card containing a cheque made out to Adam Lanza for the purchase of a firearm, authored by his mother, Nancy Lanza.
Authorities found numerous knives, including samurai swords. They found a military-style uniform in Lanza's bedroom and handwritten notes containing the addresses of local gun shops.
Authorities have said it will take until June or later for the investigation to be completed.
The massacre was one of a string of high-profile mass shootings that galvanized a heated ongoing debate on gun control in the United States. A package of gun control measures is making its way through Congress. It does not include an assault weapons ban, though states like Connecticut are considering imposing one.