(CBS News) BOLIVAR, Mo. - The Colorado theater shooting and the massacre at Sandy Hook school have raised urgent questions about the failings of mental health care. Parents are up against many barriers when they try to help a mentally ill child who's prone to violence.
Two years ago, Bill Lammers' son, Blaec, was picked up by police at a local Wal-Mart, in Bolivar, Mo., holding a butcher knife and a Halloween mask.
"What he told us was he had picked out someone," said Bill. "He was going to watch them go into the back room, follow them back there, and hopefully the police would get him and shoot him first before he did anything."
He was 18 then and already had been committed to a mental hospital twice -- once for threatening to put a pipe bomb under his teacher's car.
Blaec would be checked into mental hospitals, but could only stay for 4 days. Why the limit?
"That was our question too," said Lammers. "'Why? Why? Did you fix him? Did you cure him?'"
Four days is the legal limit without a court order. His mother, Tricia, and Bill say Blaec was in and out of mental institutions. At first, they didn't realize how serious it was. By the time he was 18 and legally an adult, it was harder to get him committed for the long-term.
His doctors would release him with new meds and a new diagnosis, everything from Asperger's to bipolar disorder to a problem linked with schizophrenia.
"I am here to love this child and to help this child in any way that I can," said Tricia.
They ran up a $50,000 medical bill searching for ways to help their son.
"Maybe it's just teenage hormones," said Bill. "You try and figure out anything but a mental condition."
Blaec's violent outbursts and manic behavior forced them to lock up their belongings. One time, he came up behind his sister holding a knife.
Tricia considered buying a handgun for her own protection, until she made a discovery while doing the laundry that changed everything.
"I found a receipt that said 'Shotgun $865,'" she said.
"And I said, 'That's not a shotgun,'" recalled Bill. "'That's an assault weapon. That's an AR-15.'"
Blaec, who had been committed seven times, "legally bought an assault weapon legally from the place [the Wal-Mart] he had walked into with a butcher knife," Bill added.
The reason: Blaec was never involuntarily committed to a mental institution by the courts, so no mental health record turned up on the background check.
A day after discovering the receipt, Tricia contacted police, who arrested Blaec. He allegedly confessed that he planned to open fire that weekend at Wal-Mart and also considered targeting the local movie theater.
On turning in her own son to the police, Tricia said: "My first thought was, 'What have I done? I just destroyed my son's life.' And people would come up to me and say, 'No, you saved our lives.'"
She added, "This is my hell. This is my hell. If I make it through this, I go to heaven."
Now 21, Blaec Lammers sits in the Polk County Jail, charged with three felony counts, including making a terrorist threat. He may face a life sentence. His parents say it could jhave been much worse, but worry that prison is not where he'll get the help he needs.