Authorities have released a report about the investigation into the Sandy Hook Elementary School shooting.

Included in the report were photos of the home 20-year-old shooter Adam Lanza shared with his mother in Newtown. Lanza shot and killed himself the day of the Dec. 14 massacre. He killed 20 children, six staff members, and his mother that day.

The photos are chilling. One shows the gun Lanza used to kill his mother laying on her bedroom floor next to a book titled "Train Your Brain To Get Happy" and another shows Lanza's bare bedroom with windows covered in black trash bags. Other disturbing items were found in Lanza's home.

The photos are posted below.

Here's an exterior shot of the house:

This photo shows the computer room used by Lanza:

Investigators found this book alongside newspaper articles from 1891 about the shooting of school children:

This photo is from Lanza's basement:

These photos show Lanza's bedroom:

This photo was taken in the second-floor bathroom of the home:

These photos show the master bedroom: