Was Adam Lanza's Shooting Rampage Inspired By Anders Breivik?

An investigation into Adam Lanza's past reveals that his mass shooting at Sandy Hook Elementary may have been influenced by another mass killing in Norway. INSIDE EDITION reports.

Video footage has emerged from the early years of Adam Lanza’s life. His mom, Nancy Lanza, captured on home video taking Adam and other little boys on a Cub Scout outing in 1996.

In the video, you can hear Nancy's voice as she tells Adam to bark like a dog, and he obeys, making noises such as, “woof, woof, woof.”

The home video is part of Frontline's Raising Adam Lanza, a joint investigation with the Hartford Courant, airing tonight on PBS.

It reveals startling new images and information about the young man who took 28 lives, including his own.

Hartford Courant reporters Josh Kovner and Alaine Griffin learned that Adam Lanza's rampage may have been inspired by Norwegian mass murderer Anders Breivik. Brevik set off bombs that killed 8 people before shooting and killing 69 others in July 2011.

Kovner said, “When police searched the house, they found some articles that would suggest his interest in this. One of the worst massacres in world history,”

Whatever was wrong with Adam Lanza culminated in the December 14th, 2012 massacre at Sandy Hook, one of the darkest days in American history.