This study examined firearm purchase behavior in relation to subsequent adverse events.
In this study, researchers developed and tested a new large-scale approach to threat assessment that relies on objective data regarding firearm purchases. The researchers found that mass and active shooters purchased more handguns overall and more semiautomatic pistols in the year prior to the attack relative to controls, potentially indicating preparation for the mass or active shooting. The researchers analyzed firearm transaction records in California to better understand the firearm purchasing patterns of mass shooters and perpetrators of firearm-related crimes and to build risk prediction models to help identify individuals who might be at extreme risk for committing such crimes in the future. Results demonstrate shorter purchase trajectories among mass and active shooters relative to controls; mass and active shooters started purchasing at an older age and reached the attack date at a younger age. A history of purchase denials was associated with 23.4 times the odds of being a mass or active shooter, suggesting that mass and active shooters have higher rates of prohibitions, and/or attempts to bypass background checks. Consistent with previous research, criminal history was the most important risk factor for firearm-related violent crime among legal firearm purchasers, with risk particularly high among those whose prior arrest is in close temporal proximity. Several transaction and firearm characteristics were associated with firearm-related violent crime, but these features provide little evidence of additional risk for those with a prior criminal record. The most important criminal history predictor was time since last arrest. This is well established in the criminology literature: risk declines over time. The next most important predictor was the number of misdemeanor arrests followed by the number of felony arrests and if the individual had ever been arrested for a violent crime.