The documents in fact provide the first detailed account of Lanza's troubled state of mind before the Newtown shooting, NBC News reported.
In a particularly shocking discovery, the warrant reveals that Lanza was able to carry out the 155-bullet shooting at Sandy Hook Elementary School in under five minutes.
The warrants additionally reveal that the house Lanza had shared with his mother was stocked with weapons.
Police also found National Rifle Association certificates issued to Lanza and his mother, a 2008 New York Times clipping about an Illinois school shooting, photos of a body covered with plastic and books about autism.
More than 1,700 rounds of ammunition were found inside the Lanza household.
The documents were originally sealed, but have been made public at this time because of the expiration of a court order, according to Reuters.