Marvin LaFontaine told the New York Daily News he believes Adam Lanza's massacre may have been an "act of revenge" due to years of bullying.
“I think Adam felt betrayed by the school and this was his act of revenge,” said LaFontaine, a friend of Nancy Lanza’s.
Lanza, 20, attended Sandy Hook Elementary School, the scene of one of America's worst mass shootings, intermittently until the sixth grade.
According to LaFontaine, he was bullied for years by classmates and harbored resentment toward the school for failing to stop it.
He recalled Nancy trying to protect her son from the taunting by turning up at the school unannounced to watch over him, a ploy which further embarrassed him.
NBC reported last week that Lanza achieved good grades while attending Western Connecticut State University in 2008 and 2009.
Records obtained by media outlets showed Lanza, who was just 16 at the time, scored high on the placement exam—in the 90th percentile. He obtained an A and A minus in computer science courses, and an A minus in American history.