They all share something else that is clearly a greater factor in rates of gun crime, that these objective scientists seemed to overlook.
The top two states for violent crime are Louisiana and Mississippi (both of which have fairly lax gun laws).
BUT a huge portion of the crime in those states is directly attributable to New Orleans, which has the highest rates of violent crime and homicide in the country. It has nothing to do with the gun laws (in fact, much of NOLA has been disarmed) but with the corrupt and incompetent law enforcement organizations in and around New Orleans.
Third is New Mexico, where much of the violence is due to spillover from Mexico due to drugs and illegals crossing the border.
Fourth is Maryland, hardly a gun friendly state.
The murder rate of a state has a more direct correlation to the presence of large cities and corrupt Democratic administration of those cities, including restrictions on firearms in those large cities (see: Detroit, Chicago, DC, Baltimore, NOLA, LA, etc)