(NBC) - Search warrants reveal that Adam Lanza, the man responsible for shooting 20 children and six adults in Newtown, Connecticut last December, had access to an arsenal of weapons in the home he shared with his mother.
When the 20 year-old went to Sandy Hook Elementary school on December 14th he was armed with a Bushmaster .223 caliber rifle, a Glock 10 millimeter handgun and a 9 millimeter Sig Sauer handgun.
154 spent .223 casings were recovered from the school.
Investigators estimate Lanza was in the school less than five minutes before he took his own life.
The documents, released Thursday, also detail items found at the shooter's home.
Investigators found books on Asperger's and autism along with the "NRA Guide to the Basics of Pistol Shooting."
Investigators also discovered a holiday card to Adam from his mother, Nancy Lanza, with a check made out for the purchase of a firearm. Adam killed his mother in their home before driving to Sandy Hook Elementary that day.
An interview conducted by the FBI revealed that Lanza was an avid gamer who rarely left his home.
Investigators have offered no insight into Adama Lanza's motivation for the shootings.
A comprehensive state police investigative report isn't expected to be completed until June