Years before 26-year-old Devin Kelley allegedly drove to a Sutherland Springs, Texas, church and killed at least 26 people, he had been convicted of violence.

According to the Houston Chronicle and ABC News, Kelley, who was previously in the Air Force, was court-martialed and convicted of domestic violence in 2012 for assaulting his spouse and their child. The conviction led to a bad-conduct discharge from the military and a 12-month confinement sentence.

We don’t yet know what Kelley’s motives may have been for the shooting, although we do know his in-laws attended the church. His history of domestic violence may be seen as a warning for what was to come, rather than the cause.

This isn’t the first time we’ve heard of something like this. Several perpetrators of previous mass shootings were accused or convicted of domestic violence in the past: Omar Mateen, who carried out the Pulse nightclub shooting in Orlando, Florida, in 2016; Robert Lewis Dear, the alleged 2015 Planned Parenthood shooter; John Houser, who killed two and injured nine in a movie theater in Lafayette, Louisiana, in 2014; and James Huberty, who killed 21 people at a California McDonald’s in 1984.

This all points to a disturbing fact: There is a very real connection between past domestic violence and a propensity to future violence, including mass shootings. Policymakers know this, but the steps that they’ve taken to actually do something about it have so far fallen far short of what’s necessary — as we saw in Sutherland Springs on Sunday.

Federal law attempts to prevent these situations, but it often fails

One of the best predictors of violence is a previous history of violence. As Pamela Shifman and Salamishah Tillet wrote at the New York Times, “Men who commit violence rehearse and perfect it against their families first. Women and children are target practice, and the home is the training ground for these men’s later actions.”

In fact, a Huffington Post analysis found that in 57 percent of mass shootings (defined as shootings in which four or more people were killed with a gun) between 2009 and July 2015 in the US, the shooter targeted a family member or an intimate partner.

Knowing this and knowing how guns can exacerbate the problem, legislators have passed laws that try to curtail domestic abusers from getting a gun. Federal law bans the sale or possession of guns for anyone convicted of a domestic violence misdemeanor or subjected to a domestic violence restraining order. Some states also task police with seizing any guns found at the scene of a domestic violence incident.

But as Emily Crockett wrote for Vox, these laws aren’t standard across the country, and they are often poorly enforced. Take, for example, the limitations in federal law: “Non-married partners who don’t live together are not protected, nor are family members other than children. It helps that federal law covers misdemeanors and restraining orders, since it’s difficult to get a felony conviction for domestic violence. But federal law only covers a full restraining order — and victims face the highest risk for violent retaliation from their abusers after an initial temporary restraining order is granted, and that comes before a full order.”

Even if people do meet the requirements for a gun purchase rejection, a background check may never catch them. It’s possible to obtain a gun through a private sale — whether at a gun show, through the internet, or via family — without ever going through a background check. And even if your state requires background checks for these types of private sales, it’s possible to simply cross the state border and buy a gun at a place that doesn’t have such strict gun laws. (This is a key driver for gun violence in Chicago, where many guns come from Indiana and other states with laxer gun rules.)

To really prevent gun violence, then, lawmakers may need to consider further relaxing requirements for gun confiscation. Some states, for example, allow police, friends, or family to request a gun violence restraining order for someone believed to pose a danger to himself or others, and the court can then impose the order to prohibit the person from buying or owning a gun for a certain period of time. Some early research has linked this policy to fewer gun deaths, particularly suicides.

And there are many more ideas, from nationwide universal background checks (supported by a great majority of Americans) to higher taxes on guns to a broader gun confiscation program similar to Australia’s.

Of course, these kinds of proposals wouldn’t just hamper domestic violence. They could also curb other forms of gun violence in the US — which America suffers far more of than other developed countries around the world.

Stronger gun restrictions could help address a very American problem with deadly violence

No other developed nation has anywhere near the rate of gun violence that America has. The US has nearly six times the gun homicide rate of Canada, more than seven times Sweden’s, and nearly 16 times Germany’s, according to United Nations data compiled by the Guardian. (These gun deaths are a big reason America has a much higher overall homicide rate, which includes nongun deaths, than other developed nations.)

What’s more, there appears to be a correlation between America’s high levels of gun violence and gun ownership, as this chart from researcher Josh Tewksbury shows:

Research reviews by the Harvard School of Public Health’s Injury Control Research Center have concluded that more gun ownership leads to more gun violence. Studies have found this to be true again and again — for homicides, suicides, domestic violence, and violence against police. Other factors (such as socioeconomic issues) contribute to violence, but guns are the one issue that makes America unique relative to other developed countries in comparable socioeconomic circumstances.

That’s one reason why where there are more guns, there is more gun violence. Here’s one chart, from a 2007 study by Harvard School of Public Health researchers, showing the correlation between statewide firearm homicide victimization rates and household gun ownership after controlling for robbery rates:

A more recent study from 2013, led by a Boston University School of Public Health researcher, reached similar conclusions: After controlling for multiple variables, the study found that each percentage point increase in gun ownership correlated with a roughly 0.9 percent rise in the firearm homicide rate.

Indeed, rigorous reviews of gun policies have concluded that stricter laws can reduce firearm violence and deaths: A 2016 review of 130 studies in 10 countries, published in Epidemiologic Reviews, found that new legal restrictions on owning and purchasing guns tended to be followed by a drop in gun violence — a strong indicator that restricting access to guns can save lives.

Domestic violence situations demonstrate why this is the case. Sadly, it’s not very rare anywhere in the world for people to attack intimate partners. But the presence of a gun makes it much likelier that violence may turn deadly. And while a gun may offer a chance for some victims to defend themselves, the overall research shows it’s simply much more likely that the weapon will be turned on the victim of domestic abuse.

One telling study from 2004, published by the US Department of Justice, compared women who were murdered by a partner with women who survived domestic abuse situations. The study found that 53 percent of the women who were murdered lived with a gun in the house, while just 15.4 percent of women who survived the abuse lived with a firearm in their homes. Based on these numbers, it seems like the presence of a gun more than triples the risk of death in a domestic violence situation.

This is the fundamental story of gun violence in America: While violence and crime occur all over the world, the prevalence of guns in the US makes these kinds of crime and violence much more likely to turn deadly.

As Zack Beauchamp explained for Vox, a breakthrough analysis in the 1990s by UC Berkeley’s Franklin Zimring and Gordon Hawkins found that the US does not, contrary to the old conventional wisdom, have more crime in general than other Western industrial nations. Instead, the US appears to have more lethal violence — and that’s driven in large part by the prevalence of guns.

“A series of specific comparisons of the death rates from property crime and assault in New York City and London show how enormous differences in death risk can be explained even while general patterns are similar,” Zimring and Hawkins wrote. “A preference for crimes of personal force and the willingness and ability to use guns in robbery make similar levels of property crime 54 times as deadly in New York City as in London.”

Taking all of this together, the empirical research seems clear: Where there are more guns and more access to guns, there are more gun deaths. And until policymakers do something about that, we can expect more incidents like the church shooting in Sutherland Springs.