Neighbours described Hawkins as a quiet teen who did not cause trouble. But recent reports have indicated the shooting did not come without warning signs.
Hawkins had gone through five years of juvenile-services programmes since the age of 13 and was charged with making homicidal threats toward his stepmother.
As a ward of the State of Nebraska, he received extensive care at Cooper Village, a residential treatment facility for teenagers, from 2003 to 2005. He was diagnosed with depression, attention deficit disorder, impulsiveness, hyperactivity, and a disorder characterised by negativity and hostility towards authority figures.
"He was in good facilities," said Sandra K Markley, Sarpy County's lead juvenile prosecutor, according to The New York Times. "He had good supervision. It didn't all go perfectly, of course. But we deal with a lot of troubled children, and, as far as we could tell, he was no more troubled than many of them."
Todd Landry, director of children and family programmes for the Department of Health and Human Services, said Thursday that "all appropriate services were provided when needed and as long as needed".
Hawkins had been removed from his home for the sake of his stepmother's safety. His father "tried hard" and participated in family therapy sessions, Markley said.
Hawkins also had an alcohol and marijuana problem.
By August 2006, the state terminated its custody of Hawkins, saying "the child is nonamenable to further services", according to The New York Times. Officials said he had refused to participate in drug treatment.
"There was really nothing more that we could offer him that he was willing to participate in," said Markley.
Hawkins' family released a statement to AP through the Rev Mark Miller of Faith Presbyterian Church in La Vista in which they said they hope the community can heal. Services had not yet been arranged for Hawkins.
"Our community of Nebraska has been confronted with an unspeakable terror," said the Rev David L deFreese, bishop of the Evangelical Lutheran Church in America (ELCA) Nebraska Synod, Omaha, in a statement.
"One of our children, so desperate and despondent, chose death as his response to the pain of living, and (he) also chose to afflict so many others with murderous agony. The horrific events overwhelm us with their senselessness and frightfulness."
Offering words of hope, the Lutheran Bishop said, "We move forward with purpose. Death and evil do not have the final word. God does."
