1. Where there are more guns there is more homicide (literature review)
Our review of the academic literature found that a broad array of evidence indicates that gun availability is a risk factor for homicide, both in the United States and across high-income countries. Case-control studies, ecological time-series and cross-sectional studies indicate that in homes, cities, states and regions in the U.S., where there are more guns, both men and women are at a higher risk for homicide, particularly firearm homicide.
Hepburn, Lisa; Hemenway, David. Firearm availability and homicide: A review of the literature. Aggression and Violent Behavior: A Review Journal. 2004; 9:417-40.