Aaron Alexis apparently came across to many as normal enough. Sure, he heard voices, saw imaginary people and believed someone was bombarding him with microwaves.

But, as far as his employer at the time was concerned, all he needed was a few days of rest. Six weeks later, while working as a civil contractor at the Navy Yard in Southeast Washington, Alexis went on a shooting rampage that killed 12 people.

Questions about why Alexis’s behavior wasn’t taken more seriously remain unanswered. However, misdiagnosing mental illness among black men has long been an acute problem — with consequences that extend beyond the Navy Yard killings to the daily gun violence throughout urban America.

“For African American males, there is a huge disparity in access to mental-health treatment and gross under-diagnosis of mental illness,” said William Lawson, chairman of the psychiatry department at Howard University’s College of Medicine. “They are much more likely to be viewed as having a behavioral problem rather than a mental disorder.”

And it’s not just the view of the larger society. There is such a stigma around mental illness that black males themselves would rather be seen as “bad instead of mad,” as Lawson puts it. The result is that they are more likely to end up in prison than to get the mental-health services they need.

A Gallup poll released Friday found that more Americans think mental illness is a greater cause of gun violence than access to guns. A 2006 Bureau of Justice Statistics report lends credence to those views: More than half of the roughly 2 million people behind bars had some kind of mental illness, and that group tended to have higher rates of substance abuse and certain violent behaviors than the general population.

Unfortunately, most of the mental-health problems weren’t diagnosed until those suffering were incarcerated.

Nevertheless, some experts warn that mental-health treatment is no panacea for reducing violence.

“What we need to control is the means through which destructive impulses are enacted,” said Janice Gump, a psychologist with a private practice in the District. “We need to control the guns.”

I am no mental-health expert, but I don’t see why we have to focus so much more on the guns than on the mind-set of the people who misuse them. Especially black people. African Americans make up only 13 percent of the population and yet account for 55 percent of homicide victims. For decades, homicide has been the leading cause of death for young black males, mostly by other young black males.

Yes, the weapon of choice is the handgun. But the question that hardly ever gets addressed is what makes so many black youngsters want to kill people who look like them?

Lawson and other mental-health experts are careful not to suggest that there are racial distinctions in the medical manifestations of mental illness. But he says that “society and culture do affect the presentation and interpretation of the symptoms.”

What we need then are better ways to interpret these symptoms.

Alexis, a 34-year-old former Navy reservist and computer technician, was treated twice in August at VA hospitals for insomnia, according to a statement released last week by the Department of Veterans Affairs. “On both occasions, Mr. Alexis was alert and oriented” and “was asked by VA doctors if he was struggling with anxiety or depression, or had thoughts about harming himself or others, which he denied.”

Black people, men especially, are notorious for refusing to admit the need for professional psychological help. Gump suspects this reluctance may be a consequence of lessons passed on since slavery, in which blacks “tend to minimize their emotional difficulties because we were told we didn’t have feelings and if we did they were insignificant.”

Going forward, mental-health services for black people must take into account the continuing impact of racism. Thomas Parham, vice chancellor for student affairs at the University of California at Irvine and past president of the Association of Black Psychologists, offered this question as a starting point:

“How do you help a black man to be mentally healthy if you have no idea what constitutes mental health for African American people in a society like ours?” he asked. “The assumption seems to be that mental health for him is the same for his white counterpart, when the bulk of the literature on black mental health says it’s not.”

For whatever reason, nothing stopped Aaron Alexis’s murderous rampage at the Navy Yard — not Veterans Affairs, not gun laws, not military security clearances and not the mental-health system. But in our search for answers, let’s not forget to focus on what may be the most important question of all: Is mental illness among black men getting the attention it so badly needs?

To read previous columns, go to washingtonpost.com/milloy.