Untreated mental illness an imminent danger? The following script is from "Imminent Danger" which aired on Sept. The correspondent is Steve Kroft. Producers Graham Messick and Coleman Cowan. The mass shooting at the Washington Navy Yard two weeks ago that resulted in the deaths of 13 people, including the gunman, was the 23rd such incident in the past seven years. It's becoming harder and harder to ignore the fact that the majority of the people pulling the triggers have turned out to be severely mentally ill -- not in control of their faculties -- and not receiving treatment. In the words of one of the country's top psychiatrists, these were preventable tragedies, symptoms of a failed mental health system that's prohibited from intervening until a judge determines that someone presents an "imminent danger to themself or others." The consequence is a society that's neglected millions of seriously ill people hidden in plain sight on the streets of our cities, or locked away in our prisons and jails. There is something eerily similar about the shooters, as if they were variations of the same person. All young males, often with the same glazed expression, loners who exhibited bizarre behavior, and withdrew into their own troubled world. They're often portrayed as villains. But Dr. E. Fuller Torrey says their deeds have much more to do with sickness and health than good and evil. Dr. Torrey: Every person I've taken care of, and I've taken care of several hundred of these people, had a very good reason for doing what looked to be crazy behavior. But in their mind, it wasn't crazy behavior. It was in response to something that was very logical, that their voices were telling them, or that their delusions were telling them. Dr. Torrey is one of the most famous psychiatrists in the country, an expert on severe mental illness, and a staunch critic of the way the country deals with it. Steve Kroft: How much of these terrible incidents that we've had, these mass shootings, is traceable to deficiencies in the mental health care system? Dr. Torrey: Well, they're directly related. About half of these mass killings are being done by people with severe mental illness, mostly schizophrenia. And if they were being treated, they would've been preventable. For example, five weeks before the shooting at the Washington Navy Yard, the gunman, Aaron Alexis, told police that he was hearing voices and being bombarded by strangers with a microwave machine. If he had been transported to a psych ward, the shootings might never have happened. In 2007, Virginia Tech student Seung-Hui Cho was behaving so irrationally that a court ordered him to seek mental health care. The order was never carried out. Cho killed himself and 32 others. And before James Holmes dressed up as the Joker and shot 70 people in a movie theater, campus police at the University of Colorado had been warned that he was potentially violent. Holmes had been a brilliant graduate student there studying the inner workings of the brain, until something suddenly went wrong with his. Dr. Jeffrey Lieberman, who is president of the American Psychiatric Association, says it's not that unusual. Dr. Lieberman: You can be the most popular student, you can be the valedictorian of your class. And if you develop schizophrenia it will change the functioning of your brain and change the nature of your behavior. Steve Kroft: You could be completely normal at age 20, perhaps a good student or a gifted student and a solid citizen, and at 21 or 22 be psychotic? Dr. Lieberman: Absolutely. Dr. Lieberman, who runs the psychiatry department at Columbia University's medical school, says that schizophrenia has a genetic component and tends to run in families, affecting the way the circuits in the brain develop. You can see the structural abnormalities in a brain scan. Dr. Lieberman: And you see people, a young adult, with a normal brain, same age with, who has schizophrenia, and you see that degenerative process has already begun. Steve Kroft: This is really a disease of the brain. Not a disease of the mind? It lies dormant during childhood and usually emerges in late adolescence and early adulthood, affecting perception and judgment. People see things that aren't there and hear voices that aren't real. Steve Kroft: What's the nature of these voices and what do they say? Dr. Lieberman: Usually it's multiple voices, talking about them in the third person, as if they're not there. They may be saying, "You're a horrible person. Everybody hates you. The only way that you can justify yourself is to lash out at them.