The National Institute of Mental Health estimates 2 million people suffer from schizophrenia

LOS ANGELES (CNN) -- After Russell Weston Jr. was released from a Montana mental hospital in the fall of 1996, he took three types of medication for schizophrenia for about two weeks, but relative say he refused to renew his prescriptions when they ran out.

Weston, described by family and friends as delusional, allegedly entered the U.S. Capitol building last Friday and killed officers Jacob Chestnut and John Gibson in a shoot- out. He remains hospitalized with gunshot wounds.

The National Institute of Mental Health estimates 2 million people in the United States suffer from one of five forms of schizophrenia. In most cases drugs can keep symptoms at bay, but there is nothing to stop patients, like Weston, from refusing medication.

"If you're free to leave a hospital, you're also free to take -- or not to take -- your medication," said Dr. Robert Butterworth, a clinical psychologist.

Many mental patients who refuse treatment wind up homeless, but only a very small percentage become violent. However, they are the ones most people associate with the disorder.

Mark David Chapman, a diagnosed schizophrenic, shot and killed John Lennon outside his New York City apartment building in December 1980. Four months later, John Hinckley Jr. shot President Reagan, his press secretary James Brady and two others.

Earlier this year, Theodore Kaczynski pleaded guilty to the Unabomber crimes after a government psychiatrist diagnosed him as a paranoid schizophrenic. The Unabomber's 17-year string of 16 bombings killed three people and injured 29.

Police tend to a victim at the Capitol shooting

Family members are usually the first to suspect that trouble might erupt. "He refused to take the medication. We've tried to talk him into it," Weston's sister, April Callahan, said after the shooting.

In such cases, experts advise families to get outside help. "Try to get help from a mental health center. There are mental health centers everywhere that will evaluate," said Butterworth.

Other mental health experts would restrict patients' in favor of public safety.

"We're talking conditional discharge or mandated commitment to outpatient treatment for a very small minority of people who have demonstrated either violence without medication or a history of being gravely impaired when they stop taking medication," said Dr. Jerry Dincin of Thresholds Rehabilitation Center in Chicago.