I'd like to know what makes them think this actually happened in the first place
This is something of a red herring though as somewhere around 75% of those murders are black-on-black, with only a minority involving Latinos. Chicago primarily attracts attention not because of its murder rate (#22 in the country vs. Detroit at #5), but instead due to the size of its population and the prevalence of violent music that has come out of the region.
https://costsofwar.watson.brown.edu/sites/default/files/pape...