The killing of six people in Tucson is one more sad episode in an ongoing series of tragedies that should not be happening. The alleged shooter, Jared Lee Loughner, is reported to have had symptoms associated with schizophrenia—incoherent thought processes, delusional ideas, erratic behavior—and almost certainly was seriously mentally ill and untreated. The fact that he was barred from his college until he was evaluated by a psychiatrist would appear to confirm the nature of the problem.

The truth is that these tragedies are happening every day throughout the United States. The only reason this episode has received widespread publicity is because there were multiple victims and one victim was a member of Congress. Such senseless killings have become increasingly common over the past 30 years, starting in about 1980, when Allard Lowenstein, coincidentally a former congressman, was killed by Dennis Sweeney. Sweeney was a young man with untreated schizophrenia who had been Lowenstein's protégé in the civil rights movement. Congress was also prominently involved in 1998, when Russell Weston, who also had untreated schizophrenia, killed two policemen while trying to shoot his way into the Capitol Building in Washington, D.C.

Over the past three decades, things have only gotten worse. A 2007 study by the U.S. Justice Department found that 56% of state prisoners, 45% of federal prisoners, and 64% of local jail inmates suffer from mental illnesses.

A 2008 study out of the University of Pennsylvania that examined murders committed in Indiana between 1990 and 2002 found that approximately 10% of the murders were committed by individuals with serious mental illnesses. There are about 16,000 homicides a year in this country. Using the Indiana study as a guide, roughly 1,600 of them are likely committed by people with serious mental illnesses.