Police in Newtown, Connecticut, were told years before Adam Lanza's 2012 killing spree that he planned to carry out a massacre at Sandy Hook Elementary School, according to a batch of documents the FBI released this week.

Roughly 1,500 pages of heavily redacted documents show that in 2008, a man told police he'd heard Lanza say he planned to kill students at Sandy Hook, along with his mother, the New York Times reports. When the man went to the cops with what he'd learned, they told him that "Lanza's mother owned the guns and that there was nothing NPD could do about it," according to an FBI file.

It wasn't the only brush law enforcement allegedly had with Lanza before he went on a rampage in Newtown, killing his mother and fatally shooting 20 children and six staffers at Sandy Hook Elementary. In an interview conducted two days after the shooting, Lanza's neighbors told the FBI that Nancy Lanza once said her son had hacked into a government computer when he was a high school freshman. According to USA Today, Lanza's mother told the neighbors that agents from the FBI and CIA came to their house afterward, and that she had to convince them her son was simply bright—that he was "challenging himself to see if he could hack into a government system."