Fifty-two-year-old Gary Carl Buoy was once a law-abiding citizen, a concealed handgun permit holder, living in Oklahoma with his wife Diana Faye Buoy. Then he shot her in the head with a .357 revolver from a few inches away. Kenneth Allen Keith, 48, a gold broker, was also a concealed handgun permit holder when he entered a pawn shop in Danville, Kentucky, and, in the course of a robbery, shot and killed three people in the presence of two children, aged nine and 14 months. The 9-year-old had to call 9-11 to say his parents were dead, lying on the floor. Marvin Arrell Stanton, 49, was at a gas station in Arkansas when he told Jessie James Hamilton to “move his fucking truck” before eventually shooting him from three feet away. Stanton was certified to teach concealed carry classes.

A talking point the National Rifle Association often peddles—and one trumpeted by everyone from Sheriff Joe Arpaio to the Washington Times, especially after massacres like the Las Vegas shooting—is the idea that the best way to stop a bad guy with a gun is to have a good guy with a gun take action. However, there is precious little evidence to support the theory, and significantly more showing that the more commonplace guns are, the more crime takes place.

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While this study itself does not attempt to discern what, exactly, this means for public safety, other recent studies have shown that states with weak concealed carry laws, or those that have enacted so-called right-to-carry (RTC) concealed handgun laws, experience higher rates of violent crime. “There is not even the slightest hint in the data that RTC laws reduce overall violent crime,” said Stanford Law School Professor John Donohue in a breakthrough study released in June, which found that states that adopted right-to-carry laws experienced a 13 to 15 percent increase in violent crime within 10 years of enacting them.