An analysis of mass shootings compiled by Everytown For Gun Safety, the gun control group organized by former New York City Mayor Michael Bloomberg, found that the shooter killed a current or former spouse or other family member in 63 out of 110 mass shooting incidents during that time period. The shooter also had a prior domestic violence charge in at least 20 of those incidents.
The report defined a mass shooting as an incident "where at least four people were murdered with a gun." The group had similar findings on the relation between mass shootings and domestic or family violence in a report issued last year.
Additionally, the groups' most recent analysis found that the victims of mass shooting incidents have been disproportionately female. While women represented just 13 percent of total gun homicide victims in the U.S. between January 2009 and July 2014, 51 percent of the victims of mass shootings during that period were female.
Read Everytown's full report on mass shootings below: