Imagine a doctor who wanted to treat a broken leg with chemotherapy. Or treat cancer with a cast.

Just because cancer and broken legs are both things that happen to the body doesn’t mean they call for the same treatment. These are the kinds of issues policymakers face every day. Take gun violence. It feels like one big problem, but it’s actually a bunch of different problems that don’t necessarily have a single cause. So when somebody wants to, say, prevent mass shootings with a policy that originated as a suicide-prevention tool, it’s reasonable to have some questions about whether that makes any sense.

And that’s exactly what’s happening with “red flag laws,” the gun legislation model of the moment, which even many gun-control-averse Republicans have supported in the wake of mass shootings in El Paso, Texas, and Dayton, Ohio. Studies have shown that state-level versions of these laws have been effective at preventing suicide. But can they actually address the separate issue of mass shootings? Surprisingly, experts think they could. And that’s because — just like a fragile, cracked bone could be a symptom of certain kinds of cancers — researchers are finding evidence that suicides and mass shootings can often be different expressions of the same problem.

“Many of these mass shootings are angry suicides,” says James Densley, professor of criminal justice at Minnesota’s Metropolitan State University.

Densley is part of a team that is working on a database of more than 150 mass shootings that took place between 1966 and 2018. His data won’t be public until January, but he said about half the attackers in his sample had demonstrated signs of feeling suicidal before they hurt others. A different set of researchers who analyzed 41 school shooters for the Secret Service and Department of Education found that 78 percent had a history of thinking about or attempting suicide.

“We’ve even talked to a couple of people who tried to kill themselves but failed and then launched an attack because they were hoping police would kill them,” said Marisa Randazzo, a former chief psychologist for the Secret Service who now consults on active threat assessment with schools and other organizations.

A third set of researchers, who compiled the details of 119 lone-actor terrorists, did not specifically track whether the people in their data set had thought about or attempted suicide, but the researchers told me they also found significant overlap between homicidal violence and choices that suggested suicidal tendencies. “A fairly sizeable subset only planned this to be a one-off event” — that is, something they didn’t return from — said Paul Gill, a professor of security and crime science at University College London and the researcher in charge of that data set. “They were taking preparations to maximize the chances of death by cop or their own hand.”

All of this means that the people who commit violent mass killings overlap, at least somewhat, with people who are feeling suicidal.

Red flag laws — which are intended to take guns out of the hands of people who might be a danger to themselves or others — aren’t going to eliminate either suicide or mass shootings, experts said. At best, these are crude tools. Plenty of people who own a gun and feel suicidal do not go on to harm themselves or attack others, and not all mass shooters were known to feel suicidal before the attack, which means the net cast by these policies will scoop up a lot of people who would never have hurt anyone while also missing some people who do go on to commit acts of violence. But enough of a pattern of suicidal feelings shows up in mass shooters that the laws might be able to reduce the rates of both.

There’s no single type of red flag law. The phrase is more of an umbrella term for a range of regulations implemented in at least 17 states. Typically, they allow people to report the dangerous behavior or mental state of someone they know. From there, those reports are evaluated and, if necessary, authorities can temporarily confiscate the troubled individual’s guns and prevent them from buying more. Once the crisis has passed, the person can get their guns back.

These rules were originally about suicide prevention, Densley told me, and were built as extensions of voluntary campaigns that encourage gun owners to give their guns to a friend if they are feeling suicidal. Experts in suicide prevention have long supported campaigns like this because of the strong links between gun accessibility and suicide. Most gun deaths in this country are suicides, and guns are the leading means of suicide. Experts say that when someone is suicidal, if they decide to act on that feeling, they are likely to turn to a familiar tool they’re already comfortable using — and when that tool is a gun, it’s particularly likely to be lethal.

And at least when it comes to suicide prevention, there’s evidence that red flag laws do work. In the decade after passing a red flag law, Indiana saw a 7.5 percent reduction in firearm suicides. In Connecticut, a red flag law was associated with a 13.7 percent reduction in firearm suicides between 2007 and 2015.

Polls show that Americans broadly support this kind of intervention, with 77 percent supporting red flag laws that allow family members to seek a court order to temporarily take away a person’s guns. And that’s true even among gun owners, where support for this kind of law polled at 67 percent. But, ultimately, red flag laws are about the state taking private property, and that can get dicey. Last year, in Maryland, police serving a red flag law order ended up fatally shooting the man they ostensibly came to save from himself. Even when things don’t turn violent, there are still civil liberties to consider. There’s no way to tell how many of the people who have their guns confiscated would actually have harmed themselves or others if they were left alone.

In the last decade, though, policy makers have begun to use red flag laws to try to prevent mass shootings as well. That makes sense in some ways, given what we know about the overlaps between suicidality and mass violence. But it also requires changing the way we think about mass shooters and how to prevent them.

Law enforcement has long tried to profile the people most likely to commit these crimes — and we aren’t very good at it, experts told me. Even once you identify some details that many of the attackers have in common, such a large swath of the population shares these traits that the “profile” is fairly useless for prevention. Red flag laws circumvent that problem by focusing less on a type of person and more on a type of emotional and situational crisis — where the people involved aren’t necessarily “bad guys” but troubled individuals in need of help. Gill thinks of it as a public health approach, analogous to the way we treat physical health problems that are hard to profile.

“We know that raised cholesterol leads to heart problems. We don’t have the ability to predict who in the general population who already has raised cholesterol will go on to have a heart attack. So we put in place prevention policies to try to decrease cholesterol in the whole ‘at risk’ community,” he said.

For the researchers who study mass violence, what’s appealing about red flag laws is that these rules have the potential to shift the emphasis from a cut-and-dried checklist of dangerous traits to a more nuanced system that accounts for a person’s big-picture emotional state. And that matters, because, it turns out, family and friends of a mass shooter are often aware that something is wrong long before the violence happens. That happened one-third of the time in Densley’s database, 64 percent in Gill’s, and 81 percent in the cases Randazzo logged.

Densley cautioned that these shootings are still extremely rare events, so the research is more about finding previously overlooked patterns than proving that a single set of traits led people to become mass shooters. What’s more, none of these research teams collected data on people who didn’t commit shootings, so they can’t say with confidence whether any of these traits are more common in mass shooters than they are in the general population. (Although Gill told me that a study that does do this is in the works.)

But right now, experts said, even when friends, family and teachers know something is wrong with a potential shooter, they may not be able to actually do much about it. Sometimes people don’t know who to tell. Sometimes they choose not to tell in order to avoid sending a loved one to prison for crimes they haven’t yet committed. Sometimes the authorities can’t do anything because the nature of the threat doesn’t include illegal behavior.

“We interviewed a social worker who had an encounter with a school shooter who had been in a suicidal crisis and [had] been admitted to the hospital before his eventual shooting occurred,” Densley said. “The social worker immediately recognized something was wrong and tried very hard to get the individual into treatment, but there were a lot of questions about his exact diagnosis and availability of psychiatric care in the community. In the end, she was unable to secure him the treatment she was trying very, very hard to get. And a few weeks later he went on to perpetrate a school shooting.”

What happens when terrorists tell someone their plans What happened after 76 lone-actor terrorists told someone what they were planning to do Type of terrorist Consequence Right-Wing Jihadi Single-Issue Average No further action 33.3% 39.3% 42.1% 37.8% Reported, arrested and thwarted 22.2 14.3 10.5 17.6 Provided aid 11.1 14.3 0.0 9.5 Police knew and no further action 7.4 10.7 10.5 9.5 Caught post-attack 11.1 3.6 5.3 6.8 Too late 11.1 0.0 5.3 5.4 Police knew and did not prevent it 7.4 0.0 15.8 4.1 Sting operation 0.0 3.6 5.3 2.7 Source: Paul Gill

All these researchers supported red flag laws because they could create a clear plan of action for friends and family concerned about a loved one’s combination of emotional crisis and violent threats. It creates a place to take concerns, a system to evaluate those concerns and a means of mitigating them. That’s particularly true, researchers said, if national red flag laws are set up so that the system isn’t punitive. Ideally, the process would focus on helping a person get through to the other side of an emotional crisis rather than putting them in jail. It’s also important, the researchers said, to make sure the laws are focused on professional evaluations of overall behavior, not checklists.

But if those parts work together the way they should, then red flag laws really could be a useful tool for combating the segment of mass shootings that function like very public, violent suicides. “There’s an important piece when we interviewed school shooters and active threat cases,” Randazzo said. “They feel very strongly about two things: They have to carry out the violence, they have no options left, but they also don’t want to do it and hope someone will stop them.”