Castillo is the young man who three years ago this month shot and killed his father and then went to Orange High School and opened fire there, slightly wounding two students, in what he has said was an attempt to replicate the killings at Columbine High School in Colorado.

He's on trial for the murder of his father, Rafael Castillo, and for assault in the incident at the high school. No one disputes that Castillo killed his father and fired at the school; the issue is whether he was legally insane when he did those things.

That, of course, is a question for the jury, and we won't presume to preempt their judgment with one of our own. But what has emerged during testimony is a portrait of a terribly unhappy and dysfunctional family, and a broken social system that was unable to prevent its journey toward tragedy.

Vicky Castillo, Alvaro's mother, said members of her family have suffered from schizophrenia, depression and other mental illnesses for generations. She herself has been subject to depression and panic attacks throughout her adult life.

She and her daughter Victoria have portrayed Rafael Castillo as a tyrannical husband and father who demanded unquestioning obedience, forced his family to live by his rigid restrictions and ruled through fear and violence. At least once, Vicky Castillo fled with her children to her native Spain in an attempt to break free; her family, she said, insisted she return.

Witnesses have said Alvaro Castillo was subject to severe psychoses and delusions, suicidal and homicidal tendencies and a dangerous obsession with guns and the Columbine shootings. His mother said he sometimes slept with a rifle in his bed, curled up with it as if it was a teddy bear, and shortly before he killed his father she went with him on a visit to Columbine. In April 2006, on the anniversary of the Columbine massacre, Rafael Castillo wrestled a gun out of Alvaro's hands to prevent him from killing himself.

By all accounts, this was a family roiled by a lethal combination of mental illness, domestic abuse and firearms. And when it finally became undeniably clear that Alvaro had become dangerous to himself and possibly others, the social safety net was too flimsy to catch him.

Alvaro was committed to UNC Hospitals, where he received mental health treatment for seven days. After that he had four sessions in the UNC-affiliated Oasis program for teens with psychosis, then was referred to a clinic in Hillsborough. The clinic had a backlog, but the therapist there was so alarmed at his mental condition that she immediately tried to get him re-enrolled in the Oasis program.

That attempt was turned down. A month later, he shot his father as Rafael sat on the couch, and then he drove to Orange High armed with several loaded guns, pipe bombs and other weapons.

Among the most alarming testimony this week was that less than two weeks after trying to commit suicide, this obviously deeply disturbed young man, 19 at the time, was able to walk into a Wal-Mart and buy a shotgun. A month after that he went to a sporting goods store in Mebane and bought a rifle.

We don't know whether Castillo was insane when he opened fire on Aug. 30, 2006. But a system that allows someone so obviously deeply disturbed to walk into a store and walk out with a gun clearly is.