the new study , by independent political magazine mother jones , was spawned by the mass shooting in aurora , colorado , in july 2012 during a midnight screening of the dark knight rises , in which 12 people were killed and 70 injured .
the magazine says it set out to determine the amount of money the survivors and victims ' families from that one incident would need , based on medical expenses , court costs , therapy and impact on quality of life .
the investigation subsequently expanded to account for all the victims of gun-related violence in the u.s. based on yearly figures from 2012 .