The focus of the news coverage surrounding the Germanwings Flight 9525 tragedy has gravitated toward co-pilot Andreas Lubitz's mental health. Reports of depression, anxiety, suicidal thoughts, psychosomatic complaints and psychiatric medications have emerged. Reaching for psychiatric diagnosis as an explanation for mass violence is familiar territory (Adam Lanza, James Holmes, Seung-Hui Cho). We crave explanation for unimaginable acts. Mental illness is something we can wrap our heads around.

I spent years in New York City working with men facing the death penalty, as a special investigator who pieced together the stories of why people commit heinous murders. I spent hundreds of hours face to face with New York's worst criminals, digging through their tragic histories. Every person I worked with had a list of mental health diagnoses. Did their mental illnesses cause them to commit murder? I didn't know.

This question led me to a two-year research study of 150 offenders in Minneapolis with serious mental illness — trying to better understand the link between symptoms and crime. I found that a very small number of crimes committed by people with serious mental illness took place as a direct result of their illness (around 8 percent). This number is consistent with other researchers who have studied the same phenomenon. So does that mean that mental illness had nothing to do with crime for the other 92 percent of cases? Probably not.

We have a tendency to dichotomize those who commit acts of violence — either they are mentally ill and commit violence because of that illness, or they are psychopaths who commit violence because they are evil. The reality is, it's a whole lot messier than that.

Untreated mental illness can make it harder to hold a job. It can make it harder to find a place to live. It makes it harder to stay connected with family and friends. Untreated mental illness can lead to self-medication with drugs and alcohol. Mental illness can lead to poverty or violent neighborhoods, pro-criminal peer groups or social isolation. Mental illness can increase impulsivity or anger.

The risk factors for mental illness and violence are quite similar — child abuse and neglect, limited resources, victimization, trauma. Stress, frustration, isolation, hopelessness, peer influence, trauma, substance abuse — any one of these factors can lead to violence. The path from mental illness to violence is not a straight one. Mental illness is often one piece of a complicated story.

And in most cases, mental illness doesn't lead to any form of violence. Studies have even found that people with a serious mental illness are less likely to commit an act of violence than others. Anxiety and depression do not make you crash a plane full of people into a mountain. The rate of depression in this country is around 8 percent (according to the Centers for Disease Control and Prevention). To oversimplify and blame mass murder on depression stigmatizes and alienates the millions of people living and working with depression in this country every day.

As a psychologist and professor of criminal justice, I know that there are things we can do to prevent violence. And I believe we can do better than turning our schools into secure fortresses or stigmatizing the mentally ill.

We can provide increased access to free mental health care and decrease the stigma around mental illness so people aren't ashamed to access care. We can fund more counselors in schools for early detection. We can provide more training and resources for stressed parents and families. We can give children access to antibullying and empathy training. More access to housing and jobs. Substance-abuse treatment. Programs that increase access to positive role models and increase social support.

We don't know why Lubitz drove a plane full of people into a mountain last month, and we probably never will. The explanations for mass violence are not simple. The solutions aren't, either. Our ability to prevent future violence depends on our willingness to embrace the complexity of the problem.

Jillian Peterson, of St. Paul, is an assistant professor of criminal justice at Metropolitan State University.