Eight of the nine killers in mass shootings in the United States in 2012 had a history of mental illness or suffered from untreated mental illness. Their families, friends, classmates, teachers or coworkers knew something was wrong.

The mass murders (defined by the FBI as four or more murders during one incident) occurred across the country -- including one right here in Minneapolis -- and targeted schools, movie theaters, stores, religious facilities and businesses, leaving 72 dead and 74 wounded. Two of the killers used assault rifles, but seven used handguns. And seven of the nine had access to legally purchased guns.

Many have called for a ban on military-style weapons, large ammunition magazines and more. The nation should consider a comprehensive federal policy.

But gun control alone will not solve the complex problem of guns and extreme violence. We have an access problem. The mentally ill should never have access to guns.

Federal law already prohibits high-risk individuals from buying guns -- persons determined by a court to be "mentally ill and dangerous," felons, drug addicts, fugitives, illegal aliens, dishonorably discharged soldiers, those who have renounced U.S. citizenship, and domestic abusers all are disqualified from gun ownership. The National Criminal Instant Background Check System (NICS) assists law enforcement in identifying the disqualified.

Trouble is, the system is woefully underdeveloped. A majority of relevant records have never been included in NICS; millions of names are missing from the federal database.

The Brady Center reports that only one-quarter of felony records have been included, and according to the National Center for State Courts, there should be as many as 2 million court judgments of dangerous mental illness in the NICS, but as of 2010 there were only 100 records submitted by 28 states.

The shooter at Virginia Tech in 2007 (the largest school shooting in recent U.S. history), had a disqualifying mental illness. Yet Seung-Hui Cho "legally" purchased the two handguns he used. He provided identification, proof of permanent residency and legal age, and for both purchases there was a 30-day waiting period for background checks. He passed both federal and state checks. Cho failed to disclose that two years prior he had been found by a court to be "mentally ill" and "an imminent danger to himself or others." That history should have disqualified him from purchasing a gun, but the records had never been submitted to NICS.

Since then, Congress passed the NICS Improvement Amendments Act to improve development and management of the NICS Index. But state participation still is voluntary, and only 12 states actively have engaged in an effort to submit mental-illness records.

Minnesota updated its laws in 2010. Our courts now are required to report all mental-health records to the state Bureau of Criminal Apprehension. However, many of our records are still in a paper form, and are not submitted promptly, leading to backlogs.

But even if we updated the NICS Index with every relevant record (and we should make every effort to do so), it still would not be enough. For a mentally ill person to become disqualified for gun ownership, there must first have been an act of violence, or an arrest leading to the extreme measure of a court hearing and decision.

In my view, this is far too late to provide meaningful care and treatment to those in need. Multiple studies show a strong link between untreated mental illness and an increased risk of committing violent acts (when properly treated, even the severely mentally ill pose no greater threat than do those in the general population).

The parents of Andrew Engeldinger, the suspected killer at Accent Signage in Minneapolis last summer, said they tried to push their son to seek treatment for paranoia and delusions, but he was an adult and refused help.

Refusing treatment and denying that help is needed both are hallmarks of mental illness. Yet that is exactly where the crisis begins, and we must assess whether a mentally ill individual presents a danger to himself or others -- without violating that individual's privacy or civil rights.

We have an epidemic of untreated mental illness in the United States. More than a quarter of adults have a diagnosable mental-health problem, but fewer than half of them receive treatment. The system is overwhelmed; the deinstitutionalization of mental health has left us with too few options and resources.

As of 2010, Minnesota had the lowest number of psychiatric beds per capita in the nation (3.9 per 100,000, compared with an average of 14.1 per 100,000 and a recommended level of 50 per 100,000). The numbers of forensic psychiatric professionals are extremely low, and those professionals are limited to seeing patients who have already committed sex crimes or other violent acts. You have to be in crisis before you can access resources. As a result, far too often, the mentally ill wind up in jail.

We need a real strategy to address this unmet need for forensic psychiatric care and to prevent those with untreated mental illness from committing acts of violence. This must become a public-safety priority as well as a public-health priority.

With the benefit of hindsight, we can see commonalities among the 2012 mass shooters: They threatened family members, committed domestic violence, expressed unusually strong interest in mass shootings (and studied them on the Internet), were fascinated with weapons, excessively played violent video games, and exhibited a disconnect from reality.

We must be more vigilant. We must invest in psychiatric-treatment doctors, beds and facilities; expand access to care for servicemembers (including treatment through community providers and not just Veterans Affairs); improve health insurance benefits (to include both inpatient and outpatient treatment), and partner with the private sector, nonprofits and faith-based organizations to develop additional community placements and resources.

More than anything, we must encourage individuals facing mental-health issues to seek treatment. We must "make it OK" for our family, friends and colleagues to seek treatment.

If you know someone who refuses help but needs intervention, please call 911. Law-enforcement agencies across the state have conducted crisis-intervention training, and we are here to help.

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Rich Stanek is the Hennepin County sheriff. In December 2012, he participated in Vice President Joe Biden's Law Enforcement Working Group on Extreme Gun Violence.