From the piece:
In his last few years, Adam Lanza shut himself off from the outside world almost completely, his troubles slowly escalating as his family splintered.
In the summer of 2010, Mr. Lanza cut off contact with his father, Peter Lanza, aGeneral Electric GE -0.81% executive whose marriage with his mother ended a year before, said a person with knowledge of family matters. It is unclear why Mr. Lanza refused to speak with his father, who made repeated attempts to contact him, this person said, but the breakdown in their relationship came as Peter Lanza started to get serious with his girlfriend, whom he married last year.
After Christmas 2010, Adam Lanza had no contact with his older brother, Ryan, who had moved away for a job in New York City, according to records and a person with knowledge of the family. And three years ago, high-school classmates recalled Adam Lanza suddenly disappearing midway through high school in Newtown, Conn. "He disappeared off the face of the Earth," according to one friend.