(MCT) — HARTFORD, Conn. — Investigators have a theory that Adam Lanza’s interest in Norwegian mass murderer Anders Behring Breivik might have led to the Dec. 14 massacre that left 20 children and six women dead at Sandy Hook Elementary School in Newtown, Conn.

The theory is based in part on several news articles about Breivik that investigators found in one of Lanza’s two bedrooms at the Newtown home where he lived with his mother, Nancy Lanza, according to law enforcement sources familiar with the investigation.