The 14-year-old boy accused of killing four people at a Georgia High School this week reportedly wrote about the 2018 massacre at Marjory Stoneman Douglas High School in Parkland, Florida, according to law enforcement sources that spoke with CNN about documents found in the teen’s home. It remains unclear what Colt Gray’s motive was, though the writings, found in his bedroom, may give investigators a glimpse into his mind in the days leading up to the deadly rampage. Portraits are already emerging of Gray’s tumultuous home life—with neighbors telling the New York Post that his family subjected him to “constant abuse.” “There were nights where the mom would lock him and his sister out of the house,” Lauren Vickers, the family’s next-door neighbor, said. “And they would be banging on the back door, just screaming like ‘Mom! mom! mom!’ and crying. It was absolutely devastating.” Gray’s father, Colin Gray, was also arrested and hit with a slew of charges Thursday night in relation to the shooting, according to Georgia Bureau of Investigation Director Chris Hosey, who said that the arrest was “directly connected with the actions of his son and allowing him to possess a weapon.”