A "trove" of video games were also discovered from the basement of Lanza's home, where he spent numerous hours playing games and honing his computer shooting skills, officials said.
Meanwhile, a Connecticut State Police spokesman rejected the CBS report, saying "All of it is speculation. There is no basis to the CBS story. We have not established a motive. It's inaccurate.”
On December 14, Lanza killed 20 schoolchildren aged 6 and 7 plus six adults before killing himself in the US city of Newtown, Connecticut, leading US President Barack Obama to push for new gun control legislation.
On August 24, 2012, Breivik was found guilty of detonating a bomb in the center of the Norwegian capital and responsible for the shooting spree at the governing Labor Party's annual youth camp on Utoya Island on July 22, 2011. Eight people died in Oslo and 69, mostly teenagers, were killed on the island.
The shooter involved in the Sandy Hook elementary school massacre wanted to kill more people than the 77 who were murdered by a Norwegian man in 2011.
Adam Lanza had been inspired by- and in direct competition - to kill more people than those murdered by Anders Behring Breivik in Norway in 2011, according to a CBS News report issued on Monday, citing anonymous law enforcement officials.
The report showed that Lanza attacked the school because he thought it was the "easiest target" with the "largest cluster of people" whose deaths amounted to some kind of game "score."