In December 2012, 20-year-old Adam Lanza shot his 52-year-old mother Nancy in the face and then drove her car to Sandy Hook Elementary School in Newton, Connecticut, where he killed 20 young school children as well as 6 adults. He then took his own life.

As a child, Adam attended Sandy Hook Elementary himself. After continuing in the Newton public school system for a few years, Nancy “pulled her son out of school to home-school him” by 4th or 5th grade. (Adam began exhibiting disturbing thoughts of violence in the 5th grade.) But then he was put back into the Newton school district by middle school. He spent part of 7th and 8th grade in a private school, St. Rose of Lima School.

While in the public school system, Adam was assigned a psychologist and “counselors, teachers and security officers were also keeping an eye on him.”  Adam was having problems at school; Nancy described her son to friends as “brilliant, but disabled.”

Adam’s disabilities had been identified early on. By age 6, Adam was diagnosed with sensory integration disorder; by middle school, he was diagnosed with Asperger’s syndrome. Despite these diagnoses, however, Nancy allegedly was angry at Adam’s school for “failing her son” and “refused to deal with them anymore” after she “pleaded for better services” for him. Adam was prescribed medication, but he refused to take them.

The former director of security at Newton School District said that, while Adam was in public school in 2007, Adam was “completely the opposite” of a killer; in fact, the school was “worried about him being the victim or that he could hurt himself.” But part way through his sophomore year in high school, his mother pulled him out a second time to homeschool him because “she was unhappy with the school district’s plans for her son.” From 8th grade on, his mother taught him humanities and his father taught him sciences. Nancy did, however, coordinate “the home curriculum with Newtown High School to insure that Adam could graduate rather than simply get a G.E.D.”

Life at home for the Lanza family was similarly chaotic. Nancy separated from her husband Peter in 2001 (when Adam was 9) and they divorced in 2009 (when Adam was 17). After the divorce, Nancy was “living alone in a big house” and purchased a number of guns. She “had five weapons registered to her,” including “a Glock handgun, a Sig Sauer handgun and a Bushmaster rifle.” Nancy not only allowed Adam access to these weapons, but encouraged his interest in them. When police searched Nancy’s house after the massacre, they found a check Nancy wrote to Adam from the previous Christmas; it was for him “to buy a CZ 83 pistol.” References to pedophilia were found on a computer hard drive alleged to belong to Adam and elsewhere around his house.

At the age of 20, when he went on his killing spree, Adam had few (if any friends) and had no job. Not long before he went on his massacre, Nancy — while frequenting a nearby bar — had expressed to a friend that “her troubled young son was spiraling out of control.”

The Sandy Hook massacre is considered the second-worst school shooting in U.S. history.