Tamara O’Neal, a 38-year-old emergency physician, was fatally shot on Monday at Chicago’s Mercy Hospital and Medical Center, where she worked. The killer was Juan Lopez, reportedly her ex-fiancé. Before Lopez shot himself, he also killed Dayna Less, a pharmacy resident, and Samuel Jimenez, a police officer.

Though many details about the crime remain unknown, O’Neal’s family said she had recently broken off her engagement to Lopez. He had confronted O’Neal on Monday to demand the engagement ring back, a police spokesperson told the Chicago Tribune.

The story, unfortunately, is a familiar one. Fifty-four percent of shootings with four or more victims are related to domestic or family violence, according to the group Everytown for Gun Safety. And many shooters, from Ian David Long, who killed 12 people and himself at a bar in Thousand Oaks, California, on November 7, to Scott Beierle, who killed two women and himself at a Florida yoga studio less than a week prior, have a history of domestic disputes, domestic violence, or hateful rhetoric toward women.

Domestic violence, unfortunately, is common throughout the world. But ready access to guns in the United States makes it more likely that abuse will turn into mass murder. “The prevalence of guns in this country coupled with the prevalence of domestic violence leads to fatalities,” said Jennifer Payne, an attorney with Chicago’s Legal Assistance Foundation, which offers free legal aid to people in poverty, including domestic violence survivors.

Federal law prohibits people convicted of domestic violence from buying guns. But because of loopholes and inconsistent laws at the state level, many abusers own guns anyway. Closing those loopholes would go a long way to breaking the connection between domestic violence and gun homicide.

“We know this is an incredibly common form of intimate partner violence, and we know how to stop it,” said Phoebe Kilgour, a spokesperson for Everytown. All that’s needed is the political will to actually do so.

Many mass shootings are also incidents of domestic violence. And many shooters have a history of being abusive.

O’Neal had gotten into emergency medicine in part to help underserved communities, according to the Chicago Tribune. She had been the director of her church choir, and was close to her family in La Porte, Indiana. Whenever her father texted her, he told WBEZ Chicago, she always texted back — until he saw news of the shooting at the hospital and asked her if she was all right.

“I texted her twice and I didn’t get an answer,” her father said. “That’s the only time.”

La Porte, Indiana residents Tom & Glenda ONeal talk about their daughter Dr. Tamara “Tammy” O’Neal, who was killed by her ex-fiancé at Mercy Hospital in Chicago on Monday. pic.twitter.com/uvSTiXfrhX — Michael Puente (@MikePuenteNews) November 20, 2018

O’Neal’s family members told the Tribune that O’Neal and Lopez had ended their engagement just weeks before they were to be married. The reason is unclear, but according to her father, it was her decision. “She broke off the engagement; he couldn’t get over it,” he told the Tribune.

Lopez apparently had a history of threatening behavior. In 2014, his then-wife had reported that he threatened her, according to Chicago network WGN. “He began sending threats via text message to come to my job and cause a scene,” she wrote at the time. She was granted a restraining order against him by a judge, according to the Tribune.

O’Neal’s murder is part of a distressingly common pattern. Last April, Cedric Anderson shot his estranged wife at the San Bernardino, California, elementary school where she taught, also killing an 8-year-old student and wounding a 9-year-old. In May of this year, 10 students were shot and killed at Santa Fe High School in Texas — the suspect was a boy who had been making increasingly aggressive advances toward one of the victims over a period of months, according to the girl’s mother. In July, dozens of people were held hostage at a Trader Joe’s market in Los Angeles, and one employee was eventually killed — the suspect is also accused of shooting his grandmother and wounding his girlfriend earlier in the day.

Other mass shooters and shooting suspects have had a prior history of domestic violence allegations. Police had been called to the home that Long, the Thousand Oaks shooter, shared with his mother earlier this year after reports of a domestic dispute. Devin Kelley, who killed 26 people at a church in Sutherland Springs, Texas, last year, had been convicted of domestic violence in 2012 for assaulting his spouse and their child, as Vox’s German Lopez notes. James Hodgkinson, who shot Rep. Steve Scalise (R-LA) and four others last year before being killed by police, had been charged with domestic battery and discharge of a firearm in 2006, after an incident with his foster daughter.

Meanwhile, other shootings have been preceded by misogynist rhetoric on the part of the suspect. Elliot Rodger, who killed six people and wounded 13 before taking his own life in Isla Vista, California, in 2014, left behind a YouTube video in which he said women who weren’t attracted to him would be punished — and he has been cited admiringly by at least two shooters since.

There’s a connection between gun violence and the kind of toxic masculinity expressed by Rodger and others. “There is a particular form of masculinity that’s been very consciously cultivated and constructed by the corporate gun lobby over the past decades,” Jonathan Metzl, a professor of sociology and psychiatry at Vanderbilt University who has studied gun violence, told me earlier this year.

Gun makers and the National Rifle Association consciously play on gender stereotypes in their ads and publications, and sometimes imply that to be a real man, you need to own a gun. And those arguments may resonate with men who feel dissatisfied or angry in their relationships.

Men interviewed at gun shows often bring up marital or relationship problems or “express resentment over the idea that the estranged spouse might try to get more financial support,” Robert Spitzer, a political science professor at the State University of New York Cortland and the author of the book The Politics of Gun Control, told Vox’s Hope Reese last year.

Gun culture in general extols “what might be identified as traditional male values of male dominance, of the man properly expressing the use of force,” Spitzer added.

Of course, most gun owners never kill anyone. And there’s a distinction between incidents of domestic violence that also become mass shootings, and mass shootings by people with a history of domestic abuse or misogyny. In the latter case, the shooting may or may not be related to prior misdeeds. But the way that guns are marketed and sold in America, specifically to male consumers, help create the conditions under which angry men may see gun violence as the answer to their problems.

Guns make it more likely that domestic violence will turn deadly. Simple policy changes could help.

One reason why shootings tied to domestic violence happen so frequently is that domestic violence itself is incredibly common. One in three women and one in four men have experienced violence at the hands of a partner at some point in their lifetime, according to the National Coalition Against Domestic Violence. And violence by intimate partners accounts for 15 percent of all violent crime.

Abuse by partners or family members is a worldwide problem, but in the United States, it’s worsened by the availability of guns. The presence of a gun in the home makes it five times more likely that a woman in an abusive relationship will be killed.

What’s more, the presence of a gun can make it more likely that bystanders and others will be harmed in a domestic violence situation. Access to guns “increases workplace violence and violence against law enforcement officers,” both of which were at play in the Mercy Hospital shooting, Payne said.

If the suspect in that shooting had been carrying a knife instead of a gun, it’s possible that O’Neal would still have been harmed, Payne said. But, she added, “the pharmacist would be alive today and the police officer would be alive today.”

A few relatively simple policy reforms would make it harder for domestic abusers to get access to guns, Kilgour said:

The “boyfriend loophole” needs to be closed. While people convicted of domestic violence against a spouse, or under a permanent restraining order, are prohibited from owning guns under federal law, the law doesn’t apply to those convicted of harming an unmarried partner. “Federal law has not kept up with modern relationships,” Kilgour said.

While people convicted of domestic violence against a spouse, or under a permanent restraining order, are prohibited from owning guns under federal law, the law doesn’t apply to those convicted of harming an unmarried partner. “Federal law has not kept up with modern relationships,” Kilgour said. The “gun show loophole” needs to be closed, too. The federal background check system is supposed to stop convicted abusers from buying guns — in fact, one in seven people stopped by the background check system are abusers, Kilgour said. But federal law does not prohibit unlicensed sellers from selling guns without background checks, which means that in many states, an abuser can still buy a gun at a gun show, online, or from a family member and use it to harm a partner. “This is one of the biggest problems for protecting domestic violence victims from gun violence,” Kilgour said.

The federal background check system is supposed to stop convicted abusers from buying guns — in fact, one in seven people stopped by the background check system are abusers, Kilgour said. But federal law does not prohibit unlicensed sellers from selling guns without background checks, which means that in many states, an abuser can still buy a gun at a gun show, online, or from a family member and use it to harm a partner. “This is one of the biggest problems for protecting domestic violence victims from gun violence,” Kilgour said. State laws need to catch up with federal law. Many states don’t have their own version of the federal ban on abusers owning guns, Kilgour said. “While domestic abusers in those states are prohibited from possessing guns under federal law,” she explained, “it often means that local law enforcement and local prosecutors don’t have the tools they need to enforce those restrictions.” Federal authorities usually aren’t the ones responding to reports of domestic disputes, and state and local law enforcement aren’t always able to enforce federal law. In many cases, “there are not state laws that empower the people who are actually out policing communities to make sure that these people don’t have guns,” Kilgour said.

Many states don’t have their own version of the federal ban on abusers owning guns, Kilgour said. “While domestic abusers in those states are prohibited from possessing guns under federal law,” she explained, “it often means that local law enforcement and local prosecutors don’t have the tools they need to enforce those restrictions.” Federal authorities usually aren’t the ones responding to reports of domestic disputes, and state and local law enforcement aren’t always able to enforce federal law. In many cases, “there are not state laws that empower the people who are actually out policing communities to make sure that these people don’t have guns,” Kilgour said. Authorities need to be able to confiscate the guns that abusers already own. Most states don’t require abusers to turn in their guns, even if they’re prohibited from buying more, Kilgour said. That means any firearms they owned before their conviction remain in the home, making it more likely that they’ll kill their partners.

These policy changes wouldn’t prevent all shootings related to domestic violence. Many abusers are never convicted, and helping survivors get to safety, report the crime if they wish, and access legal representation is critical for preventing future violence. “Only 50 percent of domestic violence victims who walk into the [...] courthouse in Cook County get any assistance at all” from an attorney or domestic violence advocate, Payne said.

But gun violence studies show that policies to reduce access to firearms have a real impact.

“Research shows that in the states that go beyond federal law and require a background check on every handgun sale, fewer women are shot to death by intimate partners,” Kilgour said. Meanwhile, state laws that require people subject to domestic violence restraining orders to turn in their guns are associated with a 10 lower rate of intimate partner homicide, according to Everytown.

In recent years, some states have passed laws allowing extreme risk protection orders, which let law enforcement confiscate guns from people who are deemed a danger to themselves or others. These laws have shown promise, especially in preventing suicides.

Earlier this year, Illinois passed such a law, called the Firearms Restraining Order Act. But the law was too late to help Tamara O’Neal: It takes effect in January 2019.