FBI data shows Illinois has recorded 38 gun-related domestic violence homicides since 2006, but the number is likely higher because the data is incomplete.  Only the Chicago and Rockford police departments report firearm-related domestic violence homicides to the FBI.  The Illinois State Police says the relationship of a homicide victim to the offender is considered supplementary data that is not required to be reported.  26 of the 38 homicide victims were either a wife or girlfriend of the offender. 31 of the deaths happened in Chicago.  Federal and Illinois state law prohibit those convicted of a domestic-violence charge from owning a firearm ever again. Illinois law also requires gun owners with a restraining order against them to surrender their firearms to law enforcement.