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If the U.S. wants to finally put a cap on mass shootings, then courts and cops need to recognize how what happens inside the home predicts what happens outside of it. In a nicely reported piece for the Huffington Post, Melissa Jeltsen details the research around the pattern, which has been grimly spotlighted by Esteban Santiago, the gunman who killed five at the Fort Lauderdale-Hollywood International Airport.

In the year preceding the shooting, Santiago reportedly had five run-ins with police in Anchorage, Alaska, including two accounts of strangulation that, to Jeltsen, “don’t appear to have been taken seriously.”

What’s so horrifying about strangulation — and so informative to police work — is that it shows a capacity to take someone’s life. A 2008 paper in the Journal of Emergency Medicine found that nonfatal strangulation preceded 43 percent of the 506 domestic homicides studied.

While mental illness isn’t a good predictor of mass shootings, a history of violence — often domestic — is. As Emily Crockett explains at Vox, while they aren’t as grabbing of national attention as public shootings, most mass shootings (defined as four or more people are killed) involve either a family member or current or former partner. The effects aren’t limited to women: An analysis of arrests in Washington State found that felony domestic violence is the greatest predictor of violent crime against men, a finding highlighted by activists Pamela Shifman and Salamishah Tillet in a 2015 New York Times op-ed.

Domestic violence is learned: Some research indicates that boys who grow up in conflict-ridden homes are four times more likely to repeat the behavior in adulthood. “Because violence in the home tends to be a child’s first experience of it and is often defended as either inevitable or trivial, it becomes the root and justifier of all violence,” Shifman and Tillet write. Childhood neglect has also been identified as a major risk factor.

Thankfully, there’s an elegant policy solution to prevent domestic abuse from escalating into firearm deaths: Anyone who’s convicted of domestic violence shouldn’t be able to buy a gun.